Tom said "I am a future incarnation of you," in about every way, other than actually uttering the words. Of course even if he said it outright, you could just then compare him to Jackson Lake, who also claimed to be the Doctor, but wasn't really.
You could claim anything with Doctor Who, really. Its a world where, potentially, anything goes. However, I do think the intention of "The Curator," is very obvious. He is meant to be the Doctor, but is written as ambiguously as possible to avoid setting him in stone (and thereby making him a plot-point that future showrunners have to deal with, ignore, side-step or whatever). He's there for two reasons;
1. To supply future information to the Doctor about the fate of Gallifrey, to imply a future story arc and to explain the presence of the "Gallifrey Falls No More," painting.
2. As a nice moment for the fans, simply because this was a special anniversary episode. Tom is the oldest surviving actor who played the Doctor and he also possibly wanted to make up for turning down appearing in the 20th anniversary. His appearance is just a little gift to the long-term fans of the show.
Now because of those reasons, I think it is both safe to make an educated deduction as to who he is meant to be and also that it is not worth dwelling on too much, as he will most likely never ever appear - or be referenced - again.