ok if this question has been answered, then please direct me to it.

Here we go. In 5 years later, Hiro has been trying to change the past so that the cheerleader is saved so that Sylar can't heal. Yet Claire is clearly still alive and the world, is that because the future is changing around him or what? Because normally when the future changes people around aren't aware of it, and Hiro remembers Sylar regenerating, yet he clearly can't regenerate as he's "waited so long" to take claire's power.

I think I may have answered my own question but what are your thoughts

Without getting back into the debate regarding specific time theories, Future_Hiro comes from the timeline where Sylar killed Claire and was the bomb.

That timeline was prevented/altered when he told Peter to save Claire. Now Claire survived and a new timeline was created. F_Hiro jumped into it when he went back to his "present"; our "future".

I see so in that timeline, Claire had been saved, but Peter had still exploded. That makes more sense. thanks

I don't know about why she is in the future when she is supposed to be dead, but if you check out the new season three preview on NBC, she seems to be up to some more mischief in the the future.