DJ6 -
I'll try to be realistic.
Whenever I go to Gatwick in summer, I see lots of flights to Greek islands not served from Luton. If there is demand from Gatwick, surely there is from Luton, although overall capacity will be limited.
I'm also struck by the paucity of flights to secondary holiday areas - Morocco, the Azores, Porto Santo, Egypt. All are within operational range, but the market must be limited to these places.
It's interesting that Wizzair have opened a number of Scandinavian routes. Time will tell as to the success of these, but if these can work, perhaps others can too.