...all the powers that he "took" from Galactus? Thor should be able to keep it after what he went through. If writers have a problem writing a story about Thor due to the power increase and would find it not challenging then that would tell you that you're not a very good writer.
Thor would know that the powers he has now would make him probably THE most powerful being in the Marvel comic book universe. But for Thor, he can turn it on and off when he needs it. When he doesn't need it, he can just go about with his natural born abilities (that is slowly evolving due to his position and growth) and the Odinforce he was given.
That would make it extremely hard to write Thor stories though, as he would be basically the new LT now!