Overreaction at its finest. I am not saying he will win the next slam or the one after that or anything like that, but the fact that you ask whether he will ever will a GS title, is really funny. He lost to Murray who was playing excellent tennis and is a beast on hard courts, and he lost only in the quarters.
Let's see how things turn out, his play especially during the clay court season, and then we can talk about such things. However, never write him off.