OK, I'll give you his fitness. Mental fitness is shot to buggery, maybe.
Rafa runs all over the court all the time too, don't forget. And won 2 Grand Slams while injured. I don't believe Andy's ankle was as bad as it was reported. Seeing how he went on to win at Queens ? 
I think Federer's reign is ending, I feel it's a shame watching him not be as fantastic to watch as he was, but I suppose it happens to everyone. I quite admire him for still giving it a shot, unlike Pete Sampras, who quit so no-one could beat him.
I don't think Andy will ever win a Slam, no. I think he had his time, and missed the opportunity. I did write a while back about this, it annoys me intensly that we get all the excuses of injury, tiredness etc, we never hear it about Roger or Rafa. You have to look at his peers to see what they have achieved in context with him. He and Rafa only have a couple of months age difference, there must be some reason why Rafa has achieved so much and Andy so little ? I'm not saying it's all his fault, but he is the one on the court playing at the end of the day, and the only one who can do it, ultimately.
I think in all likelihood if he did ever win a Slam, it would be because Roger, Rafa and Novak are all either injured in some way, or out. I don't like that Andy uses injury as an excuse for poor play, if it's that bad, then don't play ! Roger and Rafa never attribute injury to losing, they always compliment their opponent, and give credit where due. IE, "He (whomever) played better than me, and deserved to win".