If UA stops serving LHR, whether through restructuring or through liquidation, I think either NW, CO, or DL will get the rights. I think that Delta might be able to benefit the most from them, due to its market shares in NYC, BOS, southern Florida, and the DC markets. CO could benefit from their EWR hub. NW could benefit as they could serve DTW and MSP ( I think that Ber II allows a US carrier to serve LHR from MSP, though I could be wrong ). But these two markets are not as big as the JFK and BOS markets. In any case, if the proposed CO/NW/DL alliance goes through, I would expect whichever carrier gets the access to serve LHR from all cities with major operations of one of the 3 carriers. For instance, if DL got them, I would expect them to fly to LHR from JFK, BOS, EWR, DTW, MSP, etc.