Federer's era came to an end a few years ago. So that's already done and dusted. Federer is not going to win any more grand slams, I expect he'll retire in the next two or three years.
Nadal seems to be losing his dominance. He may have another one or two grand slam victories left in him yet.
Now it's the time for the weak players to step up, the players that have been living in Federer's and Nadal's shadows in recent years. These are Djokovic and Murray, they'll probably be winning a few grand slams over the next few years. It's quite shocking to see a player like Murray winning grand slams, but there you go, legends can't remain legends indefinitely and when their time expires, they leave room for weak players to win trophies.
Nadal won't win Wimbledon again, I think Djokovic may clinch it but we'll have to wait and see what happens in the grass court season leading up to Wimbledon, then we'll get a better idea of what kind of form the top players are in.
I'm not sure if Nadal will reach or surpass 17 grand slams, it looks unlikely but there's still Wimbledon and the US open left, so we'll see...