Heh. Interesting.
Notes:
Sylar may not retain powers permanently. Peter was able to draw the future after he left Isaac's. Likewise, Sylar may expose himself to the brains in question before going into action.
Nikki's power is arguable, however, in the show, powers come from using a greater percentage of your mind. Nikki's Dark side not only thinks independently, but communicates with normal Nikki and is aware of Normal Nikki's actions. (My favorite theory is that Dark Nikki is the real one and normal Nikki is the construct). This is not normal schizoidness. This particular incarnation of dual-personality is enabled and empowered by her specialness, regardless of if that specialness gives her pure superstrength, or controlled adrenaline rushes. If Nikki has Multiple Personality Disorder, as we know it, then that disorder is as evolved as she is -- based on what we've seen.
Killing people is wrong, especially so when other options are available. Dark Nikki may act out of interest in Micah, but she may also be selfesh and simply wish to protect Light Nikki, even psychoogically, out of self-preservation.
I'll be upset if Sylar is a future peter.
Sylar-Peter would have to be from further in the future than Katana-Hiro and may not know about Peter's Darkside. Peter may not have a darkside when Katana-Hiro knows him.
The jury is still out, remember...