EI-BUD, it is less populated than West Yorkshire and East Midlands region, barring some significant strategic shift it just isn’t going to happen. Sorry. Jet2 haven’t grown to be the strong business they are through duplicating costs. Quite the opposite in fact. The examples you have given are of different airlines and entirely different locations which have their own idiosyncrasies.
I maintain that the best best bet for growth in that sector would be from easyJet given that they have no coverage throughout central and Eastern England between NCL and LTN/STN. So if they show no interest, what makes you think that Jet2 -with large bases at LBA, EMA and MAN - would fare any better? Sorry to labour the point, but we were told 15 years ago that airlines would vote with their feet. They have.