Thinking back to the rumors after xy came out, and before oras was announced, that xy were to be the last pokemon games due to a declining fan base, and the initial fanbase growing out of pokemon, I definitely think Sun and Moon will either be a curveball to bring things around, or the last pokemon games. Either way, our idea of an 'orthodox pokemon game' will almost definitely not match what we see in Sun and Moon. I can see the games being based in a region quite different from the other regions we've seen, perhaps somewhere crazy like a space station near the sun/moon, or at least a way to travel to and from outer space similarly to the delta episode, which could possibly explain the odd vehicles we saw in the trailer, maybe built for interstellar exploration. Or maybe the sun and moon play an integral part in the plans of Team rocket (team sun and team moon?), perhaps having some super special awesome secret weapon powered by the sun or moon. With each generation, we see more and more variation from what we're used to, and I feel like Sun and Moon will be the most remarkably different games we've seen.