What are you talking about?
Nole and Muzza are the same era than Federer and Nadal? sure they're just one year younger than Rafa but Rafa's dominance has been short-lived because of Federer, same as everyone else. Federer is what, 5 years older than Nole? Hardly the same era!
Nole and Andy can dominate until they're 30 for sure. Look at the top 10 now. Nole is the youngest of all them!!! Fish, Tsonga, Sod, Berdych, Ferrer are having their best years after they hit 25. So I'm very confident when I say Nole and Andy are going to dominate in the next 3-4 years. They're just entering their primes and they will last until they're at least 29-30. Don't give me shit about their playing styles, for all we know Nadal can still play at his best for the next three years. Neither Nole nor Andy have had any important injury in their careers. Back pains, sore shoulders, yeah sure but everyone has them! Even federer but he doesn't like to talk about it.
Federer has not won a slam since he was 28(January 2010) but somehow the less talented Djokovic and Murray will do what Federer has not been able to do in this physical era, win a slam after 28.