Depends on the adequacy of the CA numbers in the regional feed too. If hiring picks up to the point the regional feed has to start parking AC again because the regional FOs don't upgrade because they have insufficient 121 hours, insufficient motivation, or simply want to avoid training failures in the hope that things will get back to legacies hiring regional FOs with no TPIC again, ULCC FOs without TPIC may become a hot commodity. After all, no legacy really wants to cannibalize their own regional feed.

It all depends on the aircraft cockpit seats the legacies have to fill. And right now that's an Airbus/Boeing issue.