Ya French Open SF didn't happen last year. Federer at his best can still compete with anyone at their best and that is a fact. He may not be physically the same player, but he can still hit winners past anyone. Djokovic can do wahtever he wants, it won't matter if he gets aced or has a 100 MPH forehand struck past him. Don't be a fool.
You're really bringing Andy into the equation? Aside from beating Nadal twice out of what, eight (?) meetings, Murray hasn't done shit against the big 3. Then, in terms of Australia and Nadal, it is his least successful slam, so suddenly Nadal at the this stage and from what we know is going to be a favorite for the title over Federer/Djokovic?
The only thing Federer needs to do is be ready mentally. He has struggled to peak at the right time, for the right matches. And in many of his recent Grand Slam matches, he has changed his tactics at the strangest moments. For example, in the second set of Australia last year against Novak, he was playing much more patient and took his time which allowed him to break Novak's rhythm and nearly take the set. However, after he got the lead, he went back to how he played the first set and it was then Novak who was taking his time and allowed Federer to make poor decisions in their rallies.
Either way, if you look in the past during Federer's prime, he didn't particularly play amazing in the first week of slam events, he would do just enough, or as they say, he would play as Soliderer. I've felt that the past few years he would reach his peak performance in the first week of slams and then when the second week would come, he would be spraying errors quite a bit. At the French Open this year, he did very well to peak for the second week, but at some of the other tournaments, I think he peaked very poorly. Of course it is easier said than done and you risk losing early if you just play bare minimum, but that balance does need to be maintained. Many tournament winners start out their runs shaky. Just look at Novak. At the US Open 2010, he played that really questionable match against Troicki and went on to reach the final. Then in Australia, he lost a set against Dodig and things were not looking too promising, yet he ended up winning the title. Similarly for Federer, at the Australian Open 2010, he didn't play lights out tennis from his first round match against Andreev all the way to Davydenko, but he certainly turned up the heat for his SF/F matches.
He should take a nice break after London and come back to Doha playing lackadaisical if he honestly wants any chance in Australia. Just compare the starts of 2011 and 2010. He started Doha in 2010 somewhat poor and got his ass handed to him by Davydenko, but ended up playing some of his best tennis ever in Australia. Then in 2011, he played absolutely perfect in Doha, returned the favor to Davydenko in the final but played quite poorly in Australia. It doesn't mean he shouldn't win Doha, but he shouldn't play all his cards at that event. A great example is Halle 2006. All his matches were literally tight 3 setters and he even had to save 4 match points against Rochus. But after winning Halle, he came into Wimbledon on amazing form and only dropped one set which was in the final.