All pokemon up to gen 6, including legendaries and megas, as well as deltas, will be available for you to obtain in the next and last version, 1.2.
I think I heard somewhere that they will probably not add gen 7 pokemon to Insurgence. Though Zygarde 50% is gen 6, Zygarde Cell, Zygarde 10% and Complete Zygarde are all gen 7, so they will most likely not be in the game.