The best result that could be achieved right now is for a return of Stobart Air on the Luton route if and when the Cityjet merger / takeover goes ahead. Free of the Stobart linkage and the demand to serve Southern gone, Aer Lingus branding is the vehicle that could deliver something good.
One assumes that a new larger Cityjet would have capacity given new ac orders etc. Again very much depends on the airlines priorities.