The answer of course depends on just how he performs at the slams. His ranking is going to drop, so if he runs into Djokovic in the QFs and loses an epic match and looks healthy then sure he can recovery in 2014. But I have a feeling that if he isn't making slam finals it will be because his body is just on the way out. If he doesn't hit old Nadal form for at least a little bit of this year then his career as a slam winner is over.
"Everybody has a game plan, until they get punched in the face" -Mike Tyson