I agree with you about the old guard.
I think players like Dimitrov, Tomic, Gulbis, Raonic (boo, hiss!) who were touted as the next best thing, haven't really lived up to the hype. But there are some behind them, so younger again, who might come through. I saw some bloke called Karen (first name) at one of the Asian tournaments last year who looked good (not that I'm an authority or owt), and another one called Medyesenov (or something, sure that's wrong) who also looked good. There's another Canadian one as well whose name I've forgotten who looks good.
And much as I love Pot, and I really really do, I think he has to prove himself sooner rather than later. He's got to show he can consistently beat the likes of Rafa, Djok, Fed, Murray etc, and win another biggie, or he's always going to be hovering just below the top three. I get upset when people say his US Open win was a fluke - I don't think it was a fluke by any means, but I do think he's got to win another big one soon.
Gosh, I wish I could spend my life in tennis land!