He relegated and his team was so dire I didn't bother watching many of their matches. All in all he's done alright for them though, very difficult to judge players true potential when they're playing in the bottom of the league.
He's 22 now, and to use Büttner as a benchmark, Büttner showed more/was better than Vermijl at age 22, but he played in a better football team too.
So all in all, there are players in the 20-24 years of age category available for roughly 5-8 million pounds (which is peanuts for United) in all competitions over the world who are better than Vermijl at the moment. But maybe if he joins a better team, like FC Twente or a mid-table Belgium team he will improve, slowly developing as a player.
But I assume you want to know about his future at Manchester United: I would say it's big odds on that we don't see him ever coming back to United.