Interesting post Leodis and I see where you're coming from. Can't say loosing Thomsonfly will be too much of a problem for me personally as they've let me down twice when I booked ex LBA.
Interestingly Jet2 have just sent me an Email saying 100s of extra seats are now available to Prague Mar to June due to high demand. Good to see but as you say all eggs in one basket!
Just hope someone else comes in to fill the charter gap if we do loose TUI or whatever they're called today. Still the market seems to be moving slowly avway from IT to "make your own holiday on the internet" Thats what I now do with Jet2 being my preferred way of getting there/back.