And that's fine. You can believe Hoenn may in the game or doubt it all you like, just so long as you're not pointing to some no-name blog without concrete evidence backing it up and using it to shut up your opposition.
Now then, there are reasons why Hoenn COULD be in this game. (I won't bother to go into them, I'm sure you've seen both the good and bad reasons a million times.) There are also reasons why it could take place in Unova again, or in an entirely new region, or any number of things.
Honestly, the one I'd like most is an entirely new region, but just because I'd like that option doesn't mean it's an especially likely option. I'm sure we'll find out in a couple of weeks whatever the case.
Creator of Jay's Journey (see quote!) "It's not ten years old! Therefore, it sucks!" - Nostalgia whores everywhere