I don't see Fed losing the number one spot this year unless he gets injured. Maybe after the AO if he doesn't defend it.
Federer should make the semis at least. Even playing like this, only nadal or joker can beat him. So i still see federer defending most of his pts. The real chance for players to gain on federer will be his performance on clay. If his movement, condition and passive play all are genuine criticisms, federer will feel it most during the clay season where he has a ton of pts to defend.
i dont expect murray to be completely back and odds are that roddick will have to play either nadal or joker rather than federer at the AO. Im not sure he gets throught that.