BOS is the east coast tech hub, and especially for biotech/medical devices, with a lot of links to partner companies in the EU... hence the buildup of DL for TATL flights there and for other domestic routes.
Yeah, some routes may take a hit, but I that is true for pretty much everywhere that airlines are flying. Sure B6 is big here but they've also gone the route of taking on junk fees for bags, seat selection etc etc so they are really no different than the other majors now.

Anyway, all just speculation, but fun to talk about and consider hypotheticals as we do here on FT