I think the LPL/MAN thing is a bit over stated. Both airports have a common catchment, but the market is big enough to support both. I live in Leeds and it is pretty common to hear people going to LBA/LPL/MAN (mostly LPL!) in search of flights.
LPL will still clearly do well, especially with sun/ski routes and some of the more popular city break destinations du jour.
MAN will probably have a focus on longer routes to more unusual places and possibly more business oriented service/routes too.