Triple H
Triple H is currently one of the biggest stars in wrestling, and he seems to have everything going for him that will ensure that he stays that way in five years time. He has feuded with the best, from Mick Foley to Steve Austin to the Undertaker, and knows what is needed of a main eventer. He is still fairly young , so another five years (perhaps with an extended break or two) should be no problem for "The Game." He can perform as a heel or a face, which should help in attempting to keep his character fresh and add longevity for the next five years.
While Triple H seems to have lost some of his charisma and in-ring ability since returning from serious injury in January, he has solidified himself as someone with the “major player” stigma. But more so than charisma and wrestling, Triple H has one thing going for him that puts him in better position to last than anyone else on the roster, and that is his ability to play politics. The Game knows how to work his stroke backstage and make himself the center of attention at all times. He is very protective of his spot and knows what has to be done to keep that spot. Right or wrong, that skill will keep him main eventing for years to come. Hulk Hogan and Kevin Nash did the same thing in WCW, keeping themselves on top (and others down) despite WCW needing new talent at the top. Triple H has kept himself at the top because he is a master politician, and that will keep him on top for as long as he sees fit.
Triple H also has more of a passion for the business than the majority of the wrestlers out there. He loves to be on top and will do what is needed to stay on top. He is still young, has the power and influence, and if he can stay healthy, should have no problem maintaining his control of the WWE main event scene.