We see in next week's preview that Sylar and Peter square off in front of Kirby Plaza, and both have Ted's nuclear power.
I think in the fight, since Peter knows Sylar is more powerful, resorts to nuking the city, yet everyone blames Sylar cuz he's the bad guy. I'm not sure how Mohinder, Matt, DL, Nikki and Bennet survive the blast since they were in the building next to the supposed Sylar/Peter showdown.
I agree with whoever it was that guessed that Peter gets his scar from Hiro's sword.
I think it'll be as simple as Claire walking up and putting a bullet into Sylar. Remember, he doesn't have the healing power so he's as vulnerable as anyone else. If he and Peter both start to go Nuclear, Claire can just walk up and pump a few bullets into Sylar to finish the job. Nothing says, anyone HAS to go Nuclear in the next episode. that future time-line can be changed if Peter keeps control and Sylar is killed.
She'd have to walk up behind him unnoticed. He can stop bullets with his telekenesis - that is one of the powers Peter doesn't have but will apparently get real soon.Sylar can NEVER be more powerful than Peter - you really only need Peter. As soon as Peter meets Sylar, he gets all his powers, plus he retains the powers he already absorbed from the Heroes Sylar was unable to kill - which currently includes Hiro, Parkman, and Claire. If he meets up with Niki, he then gets super strength and should be able to kick the crap out of Sylar.
That is what is annoying for me right now about this show - all you need is Peter. Like Jerry Seinfeld talking about Superman: "Why do you need anyone else? He's Superman!" That said, it is a living comic book, so I will watch it and enjoy on that level - I think there is a lot of disbelief that must be suspended to make this show go, which is completely unlike Lost, where everything must be fully explained somehow.