Stop comparing him to Federer and Nadal. They are arguably the two greatest players of the Open Era, or at least among the top five. Dimitrov could be (part of) the "future of tennis" while falling far short of that.
I think its possible that 2013 will be the last year that the tour is completely dominated by the Big Four. I think they'll still dominate in 2014, but the cracks will start to show. Federer will be turning 33, Nadal 28, and Djokovic and Murray 27. Still prime years for the latter three but not "super-prime" (21-26). What this could mean is that we'll see more upsets, and even one or two challengers sneaking in and stealing an ATP 1000 or two, maybe even a Slam.
It is not a question of if this will start happening, but when and WHO. I think "when" will begin in 2014 or 2015, but "who" is a bigger question because there are no clear top young talents coming up (which will in turn likely extend the reign of the Big Four). But if you look at the field, the most talented players age 24 and younger that are in the top 100 are del Potro, Raonic, Janowicz, Dimitrov, and Tomic; we might want to include Dolgopolov, Nishikori, and even Gulbis on pure talent. None look like all-time greats like Federer or Nadal, but at least some of them will be top 20 players and maybe two or three top 10, and just maybe one or two will sneak in a Slam win at some point. And even if the "who" don't win major tournaments this year, we'll be able to get a sense of who the future challengers will be.
So why not Dimitrov? Of that list I think he has the most well-rounded game. Again, he almost certainly won't be an all-time great like Federer or Nadal - we would have seen more by now. But that doesn't mean he couldn't rise to the top 10 and be a fixture there for a half decade or so, maybe win an ATP 1000 or two and even challenge for a Slam and for a top 5 ranking. At the least I think his name will be among those that challenge the Big Four until the next true elites come along.
