If they'd lived

BOB MARLEY survives his battle with throat cancer. Convinced that Jah has forsaken him, he, during a ganja-fueled obsession with Sammy Davis Jr., converts to Judaism. He goes off the radar for many years, only to reemerge and form a dynamic duo with fellow recluse, Cat Stevens. Combined, the two blow more middle-aged white minds than previously thought possible (from the research performed at the Caucasian Institute).
Then, in 1996, he switches up his style on y'all bitches, uniting forces w/Masta P. Their musical partnership bears such sweet fruit as the classics "3 O'Clock Road Ungh!", "Punany Conqueror", and "May I Please Have Some Carrots."

COBAIN takes boats across the Atlantic.

JOHN LENNON: Would have gone on to do everything George Harrison did, effectively killing Harrison's entire career. He also would have made more appearances on Saturday Night Live than any other performer. Furthermore, Anthologies most likely would never have happened, though reunion might have.