No third version yet
As the second of their Pokemon Direct announcements, Nintendo shared that the 3DS is getting two enhanced versions of Sun & Moon this year — Pokemon Ultra Sun and Ultra Moon.
Both versions will feature an “alternate story,” with “new Pokemon,” and will arrive on November 17, 2017 globally. If you want to see some very brief footage, skip to the three minute mark in the video below. Oddly, it seems like a compromise between the full-on sequels of Black & White 2, and the famous “third version” that the series used to put out.
We’ll probably get more information as we approach E3 next week, but Nintendo says more will be revealed “later this year.”