With Joker having been announced, they've proven that they can work with twistier, more modern footprints. With this, I feel like they've proven they have the potential to convert other crappier GCIs; Gwazi and Wildcat come to mind. Roar East should be likely too, considering how it's a clone of Roar West (I think).
I think the coasters that Six Flags would still have eyes on are:
-Roar East
-The Boss
-Georgia Cyclone
-Le Monstre
I also see them working with Cedar Fair circa late 2010s-mid 2020s.