I think sometimes things can get a bit stale and a change can help that. I know they have had success but RG aside I don't see him winning anymore slams especially if he has to play Djokovic. Although that might be the plan seeing as it seems as if has changed things with his racket to get more spin. That says he is focusing on retaining RG maybe at the expense of results on other surfaces where his spin isn't quite as effective.
I guess time will tell, I really hope he gets back competing at near his best soon as mens tennis definitely needs him.