Forget BA, I just don't understand the constant belly aching. Their hub is LHR, coming back to MAN would just screw up what is already in place.
The real issue is making MAN a hub. To do that the infrastructure should be happening now. Yes, I know people are saying there are plans, but as per usual they will be too little, too late and cause havoc.
There is an opportunity here, stop focusing and wasting efforts on BA, LHR R3 or 4 and any other airport in UK, make MAN the best/easiest to transit.