http://www.andriasang.com/e/blog/2010/09/28/nomura_kh3/
Here's what Tetsuya Nomura had to say about Kingdom Hearts 3 in the new Dengeki PlayStation:
"2012 is the 10th anniversary of Kingdom Hearts, so we'd like to do something to celebrate. However, I'll say this up front, just because it's the 10th anniversary, we still won't have KH3 out (laughs)."
See that "laughs" in there? It means Nomura might have been joking.
Of course, given that we could still be waiting for Final Fantasy Versus XIII in 2012, maybe he's not joking.
Also in this Dengeki interview, Nomura shared a few comments on Kingdom Hearts Birth By Sleep Final Mix.
Final Mix is, like past Final Mixes, a Japanese version of the US Birth By Sleep, with a bit of added content, including a couple of additional powerful bosses. Those who have a save file from the original Birth By Sleep will get a bonus of some form.
Nomura admitted that there won't be as much content when compared with Kingdom Hearts II Final Mix +. You'll recall that Final Mix + included a full PS2 conversion of Game Boy Advance's Kingdom Hearts Chain of Memories, so Nomura will probably be making a similar comparison for the rest of his life.