Not sure handling charges, etc will be lower than other operators already giving these companies business. If they are, they're low for a reason or they'll normalise pretty quickly.
I can't see how Flybe's costs will be lower than Eastern's, Loganair's or Emerald's costs. There can't be much in it even compared to easyJet or BA.
One of their competitors will have no legacy costs either. Others have profitable established routes/operations to help offset losses on competitive routes. Others have substantial cash reserves- with historic profitable operations.