I thought of the “future Justice Incarnate” idea; and while I agree they should do it, I don't think it should be the Legion of Superheroes. It should be a separate team that exists to facilitate crossovers among the various Legions; and it should exist in a supporting role, with the Legion encountering it whenever a Multiversal story arc is planned. But the focus of a future Legion book should be from a single universe, and should mostly stay in a single universe.
That said, I can see Infinite Frontier as an opportunity to build a new Legion that incorporates the best of every prior version, rather than going back to one of the former Legions.