I'm not enjoying Federer's rapid decline and will sorely miss him when he retires.
But there are some interesting players on the circuit, a high quality top 50, and it's only a matter of time before another truly great player comes along (to be honest we've been spoiled to have had three of the all time greats competing at near top form in this era).
Some players I enjoy watching that I will support after Fed:
Rafa. Say what you like about his attitude, his persona, he's a top 3 player of all time and how can you be a tennis fan and not appreciate is brilliance? Even if the rest of the field is terrible, he is always worth the watch.
Dolgopolov. Surprised he gets no love in here. I love his style, his movement has a sense of weightlessness, he's got a crafty game, he's cunning and a he's got a great precision forehand. It's a pity about his consistency and it's becoming clear he's not a regular top 10 customer.
Fognini. This guy has a great all court game and plays some of the best touch tennis on the tour. He's insanely talented and it's refreshing seeing a smaller guy having success while the rest of the field increasingly look like basketball players. I wouldn't say his Italian Casanova style has universal appeal though.
Nishikori. Similar style to Fognini, similar stature, a great striker of the ball. But his injury prone body won't allow him to stay at the top of the game. His personality is also somehow disengaging and uninteresting, though he does seem like a nice guy.
Raonic. Superb player with potential and an inoffensive, likable personality.
Gulbis. He's not boring, but he's not champion material.
Dimitrov. This guy somehow reminds me of looking at a wax figure ala Madam Tussauds. He bears a striking similarity to the real thing, but there's just something not quite right about it. His movement, his stroke, his everything looks like an imitation of Federer, but it's just not quite right, not quite perfect. Everything is a little jerky and half a beat slow. He has also shown that he doesn't have the psychological killer fearlessness of our recent champions; Fed, Rafa, Djokovic. Dimi is no spring chicken (what 23?) and he's already choked several times at clutch moments and has no notable achievements. That didn't happen with 19yo Fed vs Sampras centre court Wimbledon.
All in all, it's slim pickings. There is no champion quite like Federer anywhere on the horizon. His effortless style, textbook technique, graciousness, charm. Tennis has been lucky.