The MME route will be effected by the open skies agreement, but I cannot see it going altogether, as bmi need their regional routes to feed the future LHR-USA routes, so yes, we may loose one or two rotations a day, but I cannot see it going completely.
Also, bmi regional are a much more respected company, they have high load factors and are currently the best performing of all the bmi Group, so bare in mind that the MME-LHR route is now 100% in their hands, they have the potential to resurrect the route, whether they actually do or not is a different matter...