Just wondering though, every one says neither will win a Slam, then who will? Will Fed still be winning slams age 50 or something?
This is the million dollar question, isn't it?
I think tennis is very interesting right now, in that we wait with baited breath the next youngster to come through and really challenge, then join, the elite. (As Murray, Djokovic and, to a lesser extent, Del Potro have done these past five years.)
Impossible to say, but obviously those three will be strong contenders for majors while Tomic and Dimitrov are entering their prime years.
I would also place Raonic above them - he's been more consistent so far. Goffin, who I have admittedly seen little of, looks another contender in the future, though I doubt he'll ever be top two material.
Other than that, I imagine players as of yet under the radar for being too young will step up and overtake Tomic and Dimitrov.