I think it's possible that they announce a game that won't be a spin-off. I mean, if they'd announce it now, it'll probably be out around october/november just like XY and ORAS so it makes sense.
If it's a main-series game, my hopes are that it won't be a kanto remake , because.. just..ugh. In theory, we've had so much kanto ... RBY-graphics kanto, gsc-graphics kanto (yes, it counts because kanto is kanto and it's not like it had much of a story to begin with) , FRLG-graphics kanto , HGSS-graphics kanto... basically we've had kanto remade in some form for every generation of a console except the 3ds, so really, i don't wanna see another one.
Furthermore, I don't think it'll be another remake so soon, but at this point who knows. They did say in an interview that they try surprising ppl and going for the less-expected choices.
My personal hope is that we get a sort of prequel to the XY-verse, possibly in that mentioned region which isn't any of the other known 5. After reading the many theories concerning Zygarde, team E(nergy?) and harnessing energy, it's quite possible to make a fairly good plot out of it in a prequel/sequel to XY . I'd imagine a prequel featuring the mentioned region + kalos or something. (i'd like to see a pokemon war but we all know that deviates way too much from the hand-holding friendship is magic that is the mainstream pokemon games)
If the announcement will be a spin-off, well i wouldn't mind a ranger or mystery dungeon game.
p.S. @ nepeta100 - I loved pokemon conquest actually xD it was a surprisingly fun game