I dont think so, the only storyline he ever had was his relationship with Peyton, but now shes getting married to Lucas, there is really no reason for him to come back.
Probably not because even if they convince him to get back in the show what he could say when he sees that Peyton 'hooked up' with Lucas , especially in what case they last time see eachother and how 'said goodbye' (season 3 episodes 20-21) , but i would love him to come back 'cause he's brilliant , especially his songs (Someday also played in Episode 20 Season 3)
He can't! :( Well at least I'm pretty sure he won't. There's only 2 episodes (I think) left of the series. So unless something big happens I don't think he will. (Not to mention on IMDB it says he not filming anything for OTH)