IF Federer wanted to put in the long conditioning and training hours I think he could stay in the top 10 and have a 20-25% chance of winning any major he entered for the next 8-12 majors.
The problem is this... what motivation would he have to do that?
He's rich, has a family, and has most of the attainable records already. There's a few piddly things here and there.... but I can't even imagine where he'd draw the inspiration and motivation from.
What I'd like to see from Federer:
play less tournaments, pick and choose your spots to "put your body on the line"
I'd be perfectly fine if he won ZERO masters next year... and I'd be perfectly fine with him tanking the French Open if Nadal enters the tournament in relatively good form.
I'd like to see him go to the wall for the AO, WM, and USO and then start majorly cutting down on the fall swing, maybe only "seriously" playing EITHER Indian Wells or Miami but not both.. Playing the minimum # of clay tournies, and only Cincy... forget Toronto.