So if Sylar's consciousness is really inside Matt's head then that means theres no trace of him in faux-Nathan?
now that you say that, he probably will take it over at some point this seasonSylar keeps saying "A part of me stuck with you" so I guess he split somehow. Nathan seems to have some of Sylar's powers and memories, while Matt seems to be stuck with his personality (though he still seems to have his original power, because he is figuring out Matt's brain and has found ways to use his ability).
I will have an eye-roll if Sylar takes over Matt's body.
It'd be kind of cool if Sylar's hunger stayed with his mind. Or has that been retconned?
It hasn't really even been mentioned much anyway since they stopped trying to make Sylar a hero. If it's not retconned, it's probably going to a situation like the healing blood where no one really mentions it ever again.