Surely the Waterford team must have made a strong pitch to Flybe whilst they had a presence at Luton to no avail? Now they've gone it is highly unlikely they would start a service though I agree it is (or was) the most logical solution for a new Waterford - London route.
I always thought the ideal would be an aircraft based at Waterford which could service Luton twice daily as well as the Birmingham & Manchester routings. However, I just can't see it happening any time soon though I hope I'm proved wrong.