There are a lot of people complaining about his loan to BVB because he's not getting a lot of match-time, and some also think he is going to be sold without having been afforded a real chance here, but I don't think we can compare it to most youth player loans (eg. Macheda, Powell etc) - just training and playing with a team of BVB's standard (as annoying as that is to write, being a United supporter) will surely improve him. No matter what anyone says, no one can doubt he has huge talent and serious potential. Whether or not he is in LVG's plans for next season should not matter too much - LVG and everyone else knows that by the summer of 2017, we will have a new manager.
I may be in a minority here, but i'm still very optimistic that he will be playing regular football for us either next season (should LVG favour him) or the one after that (should LVG not), and will have a chance to make it here. The people running the club, contrary to popular belief, are not idiots - it is clear that he is not someone we should let go of without very careful consideration (and heavy compensation). He is quite highly rated, even outside (perhaps more-so) of the United fan base.
Just my thoughts, but I see him returning here an improved player. He hasn't played much at BVB, but he seems a lot more mature whenever I watch him, and has also improved his physique. Those were always the two biggest criticisms of him while he was here. I think another year and we will see where his future lies.