Jet2 may well operate a double BOH and SOU base in the future. There is no reason why Jet2 can't put two A320's into SOU when they are delivered and operate to some of the places that are more economically viable from SOU's runway.
I would be very surprised if easyJet did not respond defensively by opening a SOU base now with 2 or 3 A320's and serving some obvious routes that BOH are not doing such as Croatia, Poland, Austria, etc.
This may mean AGS needing to unlock the flood gates and allowing easyJet to do AMS, CDG, EDI, JER too.