RW20
Never say never regarding Easyjet at Southampton and I definitely don't think that just because Flybe are the in house airline it would be an issue, and I mean a big if that it bring the case that Easyjet did ever operate from SOU I think they could kill off Flybe on the sun routes and would prove more popular with passengers with a better quality product and a guaranteed year round schedule.
Although realistically if Easyjet did expand on the south coast my bets would be on BOH purely and ONLY purely because of its longer runway and spare apron capacity.