Speculation: This has never been done before, but I have a theory that Black and White Kyurem might be evolutions to Zekrom and Reshiram. Legendaries with evolutions, that would break new grounds.. Since they are new pokemon and not alternate forms, it makes some sense.
Wishful Thinking: I want my Emerald Battle Frontier City back. That was the greatest creation ever and to this day what I compare every post game battling complex against. (Seriously, Platinum's frontier is like a tiny amusement park, nowhere near the hugeness)
And as far as Hoenn remakes go, I did at first and still do find it farfetch'd and grasping at straws, but after reading the small coincidences given, I will respect this theory and enjoy it if it happens. But lets think about the facts here;
-Reprogramming the Hoenn region from it's gameboy version to ds would take time and effort, it's not as simple as adding in move tutors. Unless gamefreak has been working on this before the announcement, I'm not sure if they could add in hoenn + new storyline in 3 months. 
-Revisiting hoenn would be a lackluster experience, if it is anything like the kanto region in hgss. So much was taken out of that, and I really do not want to play hoenn on ds as much as I love it, if it would turn out like hgss's kanto. 
-Combining a second gen5 game and hoenn remakes loses out on standalone hoenn remakes. Money lost. 
-The evidance given is very small, again. It seems more like coincidence and hinting at a future remake than hoenn being in bw2.