If Jet2 have any sense the won't try and battle it out with RYR given the current climate !
They would do better to move into somewhere like Bournemouth where Ryanair's commitment is wavering, they have a set up there already and it's a good catchment. Forget STN as well they would have no chance.
God help us all if RYR put the smaller low cost carriers out of business, they are bad enough with what they have now, this looks like a deliberate attempt to put pressure on Jet2.
Good luck Jet 2 !!