Have Jet2 not competely saturated MAN if they stick to their business model ? There are only so many bucket & spade / city break destinations and surely they cover most of them now ? Increased frequency could be an option to eat up new based aircraft, but LPL could win more market share for them in the NW...which bothers Jet2 more than how many aircraft they base at MAN.
As far TA, MAN's demand as we know is mainly UK originating for leisure purposes, but the USA in now expensive for Brits so maybe even that sector is suffereing somewhat, however I see more potential chasing UK carriers for expansion over US legacy airlines. Jet2 jumps off the page but they seem content at the minute not doing it, but add to that VS and EIUK and here is where our future lies IMO. They just fit MAN better than US carriers.