Thomsonfly in its current guise, the 737 operator based at CVT and shortly DSA, will not start a base at CWL because there are insufficient 737 sized markets, not currently served by bmibaby.
It would be highly unlikely that Thomsonfly would take on bmibaby, the market is not large enough for 2 players. Air Wales and bmibaby have CWL pretty much sewn up. The only 737 size markets left from CWL are along the lines of Nice, Barcelona, Murcia, Faro and maybe Venice at a push. Venice and Nice being the only current Tfly destinations.
There are no domestic routes left, and bmibaby have europe pretty much sorted.
I may be wrong, but surely this comes down to pure business sense?
Regards
Mike