BLK-LGW unlikely to work for reasons outlined previously on the BLK thread. Low demand & a regular train service taking similar time "door to door".
As Channex stated Domestics haven't really worked for Jet2. Being based somewhere in the centre of the UK doesn't help their cause! Only longer domestic routes really seem to work these days - trains now appear to be moving higher percentages of people on shorter routes (i.e. LON-LPL/LBA/MAN)
PM is very good at repositioning the organisation and taking advantage of new opportunities so I doubt it will be doom & gloom!