The big revolution I think will be more point to point flying from the US, rather than the current hub and spoke setup.
Theres already near enough open skies form UK regionals to US, hence the upsurge in US airlines starting routes like Bristol/Edi etc. Only LHR is closed to new routes, you may find it actually concentrates capacity on the major airports as the yields are still much higher there and the alliances move slots to more profitable transatlantic flights. Do you think BMI will still be using a slot for an ERJ to Leeds when it could be a 330 to JFK.