You get to see the Tribal Societies of Rakata Prime during Shadow of Revan - they are nowhere even remotely close to a reestablishment of the Infinite Empire. All that remains are stragglers, nothing more (like on Belsavis, and Tatooine). While I wouldn't mind more content associated to the Infinite Empire (finding and exploring one of their ancient worlds maybe?), I wouldn't want to see them try to cheese up some kinda of "the Infinite Empire was only asleep and now their infinite fleets come to do battle with your alliance fleet" kind of thing, because that would S.U.C.K.