Its not. The Future shown has been changed due to the change brought about by the Heroes in Seaon 1 as well as Season 2 (the Virus) and irrevocably in Season 3 by Sylar getting Clair's power.
However, needy, power hungry, over compensating Sylar,still is. The Future has changed. It is no longer inevitable he will become President. Yet, many still think he will.
I will grant you. Attempts maybe made by Sylar. He may even succeed for a short time. As recently as "An Invisible Thread" Sylar still has Presidential ambitions and he inhabits Nathan's body so he's at least partially there...all he needs is to run a successful election; keep the others "Heroes" at bay; recover his psyche from Matt Parkman shove it back into his own body. Simple.
Its not I don't believe Sylar won't continue to seek power over others. I just think he'll discover a more "organic" way to power then the ultimately unsatisfying fiction of having to pose as Nathan Petrelli to have any of the things he really wants.
Becoming President in the guise of Nathan would be Sylar's way of seeking not just authority and ultimate power but a sense of legitimacy and being both at the apex of American Society and controlling it. He would soon discover this is an illusion. The last three President's have had their legitimacy--unfairly or not--questioned. Inevitably Sylar may find himself as much as prisoner of the Office as he if HRG had him under lock and key. It would not full fill Sylar's desires for belonging--that is being an accepted, loving member of a ruling elite family. This is something he has only in his guise as Nathan Petrelli but not as himself. (This somewhat explains Sylar's change in attitude in Season 3. If you were a relatively, poor, alone, outcast, struggling to make a living in a city famous for catering to the rich, who finds yourself suddenly accepted into the bosom of the Rockefeller family, how would you feel? )
As President Sylar would not be seeing primarily to his own wants and desires but to those of powerful families and industries, the demands of State, and the American People. If he thought Virginia Grey was needy and demanding; Luke or Maya or Alejandro annoying, just wait till he has to deal with pesky old Congress the Courts , the News Media and the American People With constant demands on his time and an in ablity to wily nilly kill anyone who was frustrating him or even use his powers without having a revolt on his hands. Inevitably Sylar would quickly tire of the role and blow his own cover as Nathan.
To a superhuman with global dominating ambitions the Presidency is a small, cloistered figure-trapped in Washington. Not an all power mobile figure, who can pick up and go as he desires and do what he wants, when he wants.
But what about his command of the army, navy, airforce, hardware and people? Nukes, etc. He wouldn't want to give that up? Would he?
What is an army of mere humans and machines against an Army of Specials? Sylar could control the nukes through someone like Micah, he could destroy, freeze ships, planes other equipment with someone like Traci.
Should Sylar meet up with the Carnies and observe Samuel he would learn learn how to control whole groups of Specials. I'm not saying he and won't continue to collect powers like trinkets for himself--ones he finds fascinating or useful. I just think he'll learn to have some restraint, and discretion about what he takes and when.
As a head of an army of Specials, Lost Boys and Girls, Sylar (Luke, for example) would have to contend with fewer people, therefore fewer demands on himself as a result. If Sylar can have the same power as all the governments in the world with a few emotionally dependent Specials, wouldn't he?
Now you see where I'm going. Its what I've been saying since I began watching the show. With the right Specials Sylar could literally control the world, he could form a new society and put him at the head of it With a gang of lost boys and girls and Sylar could rule. As time went on, Sylar's courtiers would grow and grow up they would fear him and feel the need to hide their children, should another Peter or Sylar arise.
In the meantime, some Specials would arise band together to inevitably challenge him. At least I've shown that the Presidency is hardly, in the "Heroes", world the be all and end all of positions of power.
Still, Sylar may change or be further altered by circumstances or come to other conclusions, join or he may stop being Sylar, possibly temporarily or even suffer decapitation from a Future Rampaging Clair. My point is the Future is not going to be the one in "Five Years Gone" whatever happens.
