I agree that Jet2's days are probably numbered on the LGW route.
But regarding Flybe's intentions, let's inject a dose of realism here. Let's assume they buy Jet2's LGW slots (although presumably others are also in the market for these). Now would they really use them to do a LGW/NQY service, where there are already four flights daily operated by WOW, a daily BA service, and a twice-daily NQY/STN service by Ryanair.... or use them to operate LGW/NCL which is a "warm" route, with a large market, uncompeted, and probably ideally suited to a 70ish seater.
I know what I'd do!!