This is just a theory I have had for a while but with mega evolution sets coming back I believe next Gen we might see gx cards again.
Theory 1: we will only see them for the 30th anniversary and then get a new rarity.(although I think its easier to use old ones
Theory 2(my favorite): we will see gx cards again, some with special traits kind of like terrastrialization and some just regular. Then pikemon may release a game revisiting things from sun and moon. That part isn't necessary but then we may see tag team sets reiterated again. That would be the best possibility.
by StillCaptain7474