EGCC4284,
I see where you are coming from but I think that with a bit of planning they will get away with this. BA will still recieved the vast majority of the fuel they need for Long Haul US flights, with the remainder of the percentage being ferried in on Inbound US flights.
AA and UA will simply use the BOS/JFK/ORD etc etc flights to ferry in fuel to top up the LAX/SFO etc etc flights.
All the Far East carriers will stop en-route in Europe/Middle East......so I personally think any diverts will be kept to an absolute minimum, there again if we could get a couple of RVR days with some holding.........
Time will tell.