TCX is likely to go down the B737 route as opposed to the A321 due to range issues as a fleet replacement for the ageing 757s and coupled with the fact that they already operate A330s, a deal to buy Excel would appeal.
Surely if they were to get a replacement for the 757's it would be the A321! They already have a large A320/321 fleet so why bother add the 737 which would require a massive change of crews, maintenance etc. They already operate A330, B767, B757-300, B757-200, A321 & A320! Talk about chaos adding the 737 aswell! My money is on a long term fleet plan of A330, A321, A320.
Range Issues? Well they would have more range issues with the 737! The only option would be the 737-900ER as they have a perfectly good A320 fleet so 737-700/-800/-900(non ER) would be a step in the wrong direction
. As for implementing the -900ER well thet would be plane stupid (hehe) when the A321 can do everything the -900ER can yet without the massive implementation costs.
Do TCX really need any more A330's? Surely 6/7 depending upon season is enough and the 767's could be reconfigured for any near long haul expantion.
But surely Thomas Cook wouldn't be interested in XL, if they needed more aircraft (which I believe they dont at the moment) then why go through the bother of another merger/acquisition when it is much easier to buy them! Also, the Thomas Cook group has made it clear that they are not out to be bigger than TUI, but to be number 1 in the markets they serve in terms of quality.