DPP and BW also essentially used the same engine and they're considered different gens. Sun and moon improved a lot more than just backgrounds. The characters in the overworld are normal sized instead of weird chibi's and it looks more "clean" (i think that's the word) as well. New starters and region basically confirms this as a new gen as well. It's weird that GF didn't follow the same tradition of new gen - remake - sequel, but they've broken this tradition before in the BW days with no remakes.Other thoughts: I love the sand castle thing, instantly being on my team. Another thing, is it confirmed that this is gen 7? And by that I mean has it been officially confirmed by TPCI. It seems more like this is gen 6.5. Even though I thought that was non-sense before, it seems like that's what it is. I feel like the game's sequel will really be 7th gen. Think about it: We can't transfer from X,Y,OR, or AS, just Red and Blue. The graphics are almost the exact same engine(other than some of the new updates to the backgrounds). And the alolan forms completely push the regular forms out of the region, so how do we evolve them? it certainly has something to do with how Glaceon and Leafeon evolved. But rather than evolving to adapt to the environment(short range), it's to adapt to the entire region. Those are the first thoughts I have about this region(Since I wasn't on the hype train at all until now). But with this comment ending, think about this:
If we bred the older regular form Pokemon with the new alolan forms, what form would we get?
Regarding the alolan version of certain mons, i think it's safe to say they're a completely different species in the same vain as polar bears and grizzly bears (who were previously the same species). If you bring a fire vulpix to alola and evolve it, it'll probably just evolve into fire nintales, even if brought to the same location ice vulpix and ninetales resides. The only exception i could see for this rule is exeggutor, since it's pre-evolution is unchanged, but that's just my thought and that may not be true. We'll have to wait for more information regarding breeding, but i suspect it's the same as always. If you breed a female ice ninetales with a male fire ninetales, you get an ice vulpix and if you breed a male ice ninetales with a female fire ninetales, you get fire vulpix (and that's if they're still in the same egg group). All just speculation of course.