With regards to TUI, it's worth noting that they do sell holidays using easyJet flights and on that basis they do still offer a decent package holiday programme from LTN, including the destinations mentioned.
I know this is probably not the right forum to say it with any agreement, but I do think they'd be as well switching the single LTN based airframe to STN, which has two aircraft currently, but with the absence of easyJet their package holiday programme is far more reduced. I know there's the Jet2 factor there but TUI do compete directly with them elsewhere in the UK and I believe they could offer a more competitive package holiday programme all round if they consolidated their own flying programme to STN and just offered LTN using easyJet flights, as they do at LPL for instance.