WOW air are throwing some very competitive fares into the market, mostly on the US side of the operation. I saw USD299 return for BOS-BRS recently, and the lead in fares to NYC are equally price busting. I recently priced up a LHR-NYC for GBP365 return, so whilst there's lots of TATL volume, the margins must be wafer thin.
None of that works particularly in favour of a "legacy" airline successfully operating BRS (or any UK regional airport) to the US. I still feel that supporting the hub routes to DUB/AMS/FRA/MUC/(KEF?) is the best way to make it easy for West Country people to get to the USA.