I have heard that there is a chance that there will at least some negotiations between the US and UK sometime this summer. That will follow a goodwill gesture that the UK will offer towards more access to LHR. A gesture that will remain regardless of how the openskies talks go. I also see that BMI is recruiting people at LHR.
I have long felt that the reason that BMI does not use the 3rd pland and soon the 4th one is that this gives them more options should a breakthrough come in the openskies. This way no service would have to canceled etc to use the aircraft for flights from LHR.