If RE can make the routes like BRS, ABZ, GLA, EDI etc work on the back of US bound or originating passengers then FR cannot extert too much pressure.
Certainly the point to point fares have gone through the roof where the ATR was brought in. Aer Lingus and flybe comparisons fail when one factors in legacy and unionised workforce versus (almost) clean sheet of paper. This idea about feeding the US routes with turboprops isn't new. The Glasgow Herald spouted the same line when Aer Lingus pulled the B737s out of Glasgow in 1991 and replaced them with the Fokker 50 operated by Aer Lingus Commuter at an increased frequency. Does this sound at all familiar? It wasn't a gold mine then and it's not going to be enough to make a real impact outwith the summer peak, also given EI are downsizing US operations as they can't make anything work outside leisure East Coast and Chicago.
As to smaller aircraft, why they didn't downsize some options to say...the A319 is beyond me. File that one next to competing head on with easyJet at their biggest base perhaps?