i don't think sasuke will be trained directly by orochimaru, but sasuke will use orochimaru to become stronger than he already is with cursed seal. that is why i think kishimoto had orochimaru already switched bodies (i think that's what happened) and make it that it will take another several more years for orochimaru to switch bodies again so sasuke can become stronger in that time period. i believe that sasuke knows the consequences of dealing with orochimaru but he knows that's what he has to do to become stronger than itachi. again, i will bring the dbz reference. vegeta let himself be taken over by babidi so he can become stronger than goku, even thought he knew he'd become babidi's puppet. so, i don't think sasuke will head back to the leaf with naruto. cuz if he does (i said this in other posts before), the whole point of sasuke getting the cursed seal, fighting naruto, and leaving the leaf in the first place would be a total waste.