The issue for CWL is that TCX were only a summer operation. That would likely rule out any Airline opening a base as there would be better options throughout the country in replacing TCX. It is however an opportunity for the like of VY or FR that could open or grow routes from other Airports. Unfortunately there aren't many options for CWL like there are at other Airports.
TUI however have stated specific Airports in their press release, although I think this is just media spin and spreads to more Airports than just those mentioned. DSA is mentioned that wasn't a TCX base, but is a current TUI base competing with LBA, MAN and EMA. I wouldn't write off TUI expansion at CWL just yet.