Fl_dutchman dont know who provides your gossip but they are wrong.
Jet2 will have a busier summer next year than this year, all routes will be returning and there are plans to have 3x 757s and 2x 737s (with 1 757 possibly being a 767 if it turns up) Thre have always been big plans for NCL for Jet2 so I cant see MJV being the only route.
As for the PMIs and AGPs if you call an average load of 220 on a 235 seater 757 poor performance then yes they arnt doing good.
Most routes are busy, LGW is also gettin a bit busier now, my mate tells me they are now gettin the pax figures up, and u can now buy gatwick express tickets on the flight now apparently