Would they announce a summer 2020 launch in Q1 2019? Maybe to get ahead of other bookings?
I really can't see the logic behind a CWL and BRS base. It would mean extra costs for crew facilities and other overheads. TCX and TUIs bases are historical consolidations of other Airlines/Tour Operators going back many years but id say the biggest consolidation being MYT/TCX and FCA/TOM into just 2 Tour Operator/Airlines. IF it were to happen it would be one or the other. Both serving the same markets. I think the decider would be the deal CWL could give them over BRS and space available, given that we all know BRS is the stronger market.
Personally I'm not holding out for an announcement as it's been talked to death over recent years and the source isn't reliable. IF it happens, it happens.