The preacher in him would have continued speaking out against injustice, war and maybe even pop culture. He would likely not have run for president. He probably would have endured more harassment from J. Edgar Hoover.
Four decades after the Rev. Martin Luther King Jr. fell to an assassin's bullet, colleagues and biographers offer many answers to the question: What if he had lived?
For his children, however, the speculation is more personal. They know their lives would have turned out differently had they had their beloved father to guide and teach them.
Instead, history moves on, remaking the world in myriad ways. The nation has grappled with issues of race and inequity without the benefit of King's evolving wisdom. A generation has come of age celebrating him in a national holiday, like other figures of the frozen past.
But given the trajectory of his life - from his appearance on the national scene during the Montgomery, Ala., bus boycott of 1955 to his death on a second-floor balcony of the Lorraine Motel in Memphis, Tenn., on April 4, 1968 - some of those closest to him have a good idea what King might be doing now, and where we might be as a country.
In the months before his death, King was speaking out against the growing U.S. involvement in Vietnam and was working with other civil rights leaders on a Poor People's Campaign, with a march on Washington scheduled for that May. He was in Memphis that spring day to support striking sanitation workers.
Were King alive today, the disciple of Mahatma Gandhi would most certainly be speaking out against the Iraq War, says King biographer David J. Garrow. However, citing the famous "Drum Major Instinct" sermon King delivered from the pulpit of Ebenezer Baptist Church in Atlanta just two months before his death, Garrow says people might be surprised to hear echoes of presidential candidate Barack Obama's controversial former pastor.
"God didn't call America to engage in a senseless, unjust war," King said of the fighting in Vietnam. "And we are criminals in that war. We've committed more war crimes almost than any nation in the world, and I'm going to continue to say it."
While King didn't go as far as the Rev. Jeremiah Wright in suggesting that God "damn America," he predicted that the almighty might punish this country for "our pride and our arrogance."
"And if you don't stop your reckless course," he imagined the deity admonishing, "I'll rise up and break the backbone of your power."
Garrow and others feel comfortable saying that King would not have sought elective office.
In 1967, King was being courted by the "New Left" to make a third-party run for president on an anti-war ticket with the renowned pediatrician, Dr. Benjamin Spock. FBI wiretaps reveal that King gave serious thought to running, but ultimately decided that his role lay outside the political arena.
The Rev. Joseph Lowery, who co-founded the Southern Christian Leadership Conference with King and marched alongside him, doesn't think time would have changed his friend's mind.
"I think Martin was a preacher, and I doubt very much if he would have wanted to subject himself to the need to compromise and play certain games that are requisite to political candidacy," says Lowery. "I think he would have preferred to do what he did best, and that was point out to ALL candidates and ALL officials ... 'Thus sayeth the Lord."'
Had he chosen that path, his enemies - chief among them FBI Director Hoover - would have laid bare potentially embarrassing details of King's personal life.
Then-U.S. Attorney General Robert F. Kennedy authorized the wiretapping of King's home and offices in a campaign to ferret out communists. The secret recording campaign failed to prove that King was a communist, but it did provide evidence of the civil rights leader's extramarital affairs. William C. Sullivan, head of domestic intelligence under Hoover, told a congressional committee that King was subjected to the same tactics used against Soviet agents and, "No holds were barred."
Hoover's office was unable to marginalize King with his supporters or cow him into silence with threats of exposure. But how might King have fared in the Internet age, when every peccadillo is exposed and every word parsed in a 24-hour news cycle?
The late Hosea Williams, one of King's chief lieutenants, once told Martin Luther King III that his father was "unstoppable" because he had conquered the two things that made men most vulnerable: the fear of death and the love of wealth.
Some, however, feel King's influence was on the wane and that at the time of his death he had already reached the zenith of his public career. He had "run out of things to do," the late Chauncey Eskridge, a King attorney, told Garrow.
"The painful truth is that in his last two months or so before he was killed, King was so exhausted - emotionally, spiritually, physically - that a lot of the people closest ... to him were really worried about his survival, his survival in the sense of would he have some sort of breakdown," Garrow says. "It would be expecting something truly superhuman, literally superhuman, for King to have continued the pace of life he had lived over those 12 years for another 12 years, never mind for another 20 or 40 years."
Journalist, author and commentator Juan Williams wonders whether King would be able to connect in a meaningful way with today's youth.
Although he was just 39, the 1964 Nobel Peace laureate's insistence on nonviolence was bumping up against the burgeoning black power movement, says Williams, author of "Eyes on the Prize" and more recently "Enough: The Phony Leaders, Dead-End Movements, and Culture of Failure That Are Undermining Black America-and What We Can Do About It."
"The big issue would be whether or not when he spoke out against the excesses of the rappers, for example, or when he spoke out on the high number of children born out of wedlock, whether or not he would be lumped in with the Bill Cosbys of the world ...," Williams says.
But he has no doubt King would be a force on the international stage.
"I don't think he'd be in the petty fray in the way that we think of some of these civil rights guys who are kind of ambulance chasers," says Williams. Instead, he sees an elder King as a man of "some standing, some stature, that people wait to hear from him... I think of Nelson Mandela in this way."
Lowery says that when King died, part of the nation's conscience died with him. Four young children lost something much more personal.
To Marty, Yolanda, Dexter and Bernice, the baby, Martin Luther King Jr. wasn't the icon or the dreamer. He was Daddy - the man who smelled of Magic Shave and Aramis and chlorine from the YMCA pool where he taught his sons to swim, and of the long-stemmed green onions that somehow fell outside the prohibition against eating before the evening blessing.
One of Bernice King's fondest memories is of the ritual she and her father shared when he'd return from a trip, like the time he came home for her fifth birthday party on March 29, 1968 - a day late because of a march in Memphis. She would jump into his arms for the "kissing game," in which each member of the family had a different spot on his face. Bernice's "designated spot" was his forehead.
Had her father lived, the 45-year-old minister is fairly certain she would be married and have children by now. But his graphic death and ponderous legacy, she fears, have made her a less than "viable candidate" for domestic bliss. Part of the problem is that her father set the bar so high. She remembers something her mother often said.
"She said, 'I didn't marry a man. I married a mission,"' the daughter says. "So for me, a spouse is more than just a companion. It's someone to fulfill your destiny with. And I think in my case, because the destiny is so great, because you had a man whose life was cut short and there was some work that had to be completed, that you now have a responsibility to participate in, that makes it a little more difficult."
Martin III, likewise, feels he wouldn't be having his first child at age 50 had his father not been killed. "I wasn't clear that I even wanted to bring a child into the world," he says.
Both siblings are quite certain, however, that their father's death did not determine their career paths.
"I don't feel like I could have been exposed to what my father and mother were doing without being involved in this movement," says Martin King, president of the nonprofit group Realizing the Dream.
Each year as the assassination anniversary approaches, legions flock to the Lorraine Motel, which now houses the National Civil Rights Museum. Among those who made the pilgrimage last week were two lions of the civil rights movement - U.S. Rep. John Lewis and the Rev. Jesse Jackson.
If King were alive today, Lewis has no doubt he would be speaking just as forcefully and with as much authority as ever about the issues that matter most to Americans, old and young.
"He would be the undisputed leader," the Georgia Democrat says. "Martin Luther King Jr. 40 years later would still be speaking out against poverty, hunger, against violence, against war."
Jackson, then 26 years old, was in the parking lot of the Lorraine that day, talking up to King when he was shot. During his recent visit, the aging activist stepped over a low wall meant to keep out ordinary tourists, climbed the stairs to the balcony where his mentor lay dying, and wept.
King would be 79 now, but Jackson feels his power to move would remain undiminished.
"He might not be leading the marches, but he would have set the frame of reference," says Jackson. "His voice would be a voice of great moral authority."
Of all the "might be's" and "what if's," MLK III feels sure of one thing. Had his father lived, the country would be closer to realizing the "beloved community" he'd envisioned.
Still, he feels his father's guiding force pulling us inexorably in that direction.
"From my perspective, his light still shines," he says. "His voice, his message, we're living every day. We're embracing more and more. We're not as close to it as I would like to see us, but we're still living it. We're still moving toward it."
So, in that way, he lives.
EDITOR'S NOTE: AP writers Woody Baird and Jason Bronis contributed to this report.