US isn't interested in the BOS-PHL market and that's why WN lost its bet. US is selling TATL & TCON xPHL and B6 isn't doing that. This won't affect US pricing much at all (take a look at the DCA-BOS USS pricing vs. B6 pricing for the same route).

But, if you commute on the route, just switch to B6 for that trip and you can take advantage of pricing designed for O&D traffic.