I wouldn't worry about EZY coming to SOU. EZY would never order the C-series, it goes against the simple LCC principle of having one type of aircraft. Also both EZY and FR are increasing capacity on their aircraft to continue to bring costs down so ordering small aircraft would not happen. Whenever EZY open new bases in the future it will be at airports such as FRA, MUC, LHR, ZUR to compete with the flags on business routes, not regional airports.