It was spoiled a while ago that in season 3 both nikkis and micas storyline ends.
So they will either both die or just leave there (I prefer the later....).
Monica vs Knox was supposed to be the main storyline in season 3.
However all of those things were to go that way before the strike occured, the cancellation of volume 3 Exodus and before they make out of volume 4 villains a volume 3 and now actually Season 3.
So they could go many ways but we can't tell which ones.
As far as I can tell Nikkis character had lots of potential and many ways to go but they wasted the storyline of the whole family over two seasons by coming up with another sucky personality (gina) and use nikki only for a few scenes whining AGAIN as if we wouldn't have enough whining of the queen of whining named claire in the show....
They killed D.L., used Micah for a few scenes and Nikki only to further Nathans and other peoples story again.

Sylar in my opinion is OVERDUE and in season 2 he was supposed to get killed by elle.
The strike saved his butt so..... He got lucky again.

I really hope that if nikki and micah die that it won't be sylar cause I'm totally bored by this sucky character and having seasons 1 power hungry sylar again would add nothing to the show.