He is taping his knee at 23/24 and has become more defensive player than in 2007 when he was more aggressive and you think he will age as good as Federer?
contrary to Federer he doesn't need to turn around his backhand, that's a great advantage.
Even among lower-ranked players you can see that's a big character of players aging well.
Unfortunately his serve is not good enough (which is in Fed's advantage in that case), and my main physical wonder would be about his shoulder.
The fact that he tapes his knee now doesn't mean so much if it's not a big/chronical problem, but probably he should be more careful at the extensions of his body in defense.
Overall I would think he would age "like Federer".