Just my opinion of course, but it wouldn't surprise me if the route was losing money due to the inferior Y product and the aforementioned delays/cancellations. I refuse to believe it's entirely down to MAN not being as lucrative as, say, the London market as others are demonstrating with their growth in recent years. That said, it's still a loss nonetheless.
As others say, it's an opportunity for VS/DL, United and Thomas Cook to increase their market share and hopefully this will make the future of their offerings more secure if sufficient AA customers don't want to travel via LHR/DUB/ORD/PHL. In the case of VS/DL, it's probably too late for this winter but maybe it could lead to a more frequent schedule being run next winter?