I would expect to see Faro and Malaga frequencies stepped up significantly next summer by easyJet and to a lesser extent Jet2.
While I have enjoyed flying Aer Lingus for business and pleasure ex Belfast International, they need to realise what they are competiting with especially on Gatwick. Flybe does codeshare with BA, interlines with other airlines including Virgin, Emirates etc. Southampton complements Gatwick route with the opportunity to fly into one and out of the other for a return trip and this may suit some as the airports are not awfully far apart.
Sadly, when I need to get to LHR side of town it will be Luton with easyJet (I think easyJet could step LTN up in light of AerLingus withdrawl), or to BHD for BA or EI.
EI-BUD