If all things go well with us, he'll have a big decision to make in the summer. If he continues to excel with us, he'll sadly be no closer to being Man Utd's No. 1. De Gea is 27 and now that RM have Courtois, will be Man Utd's No. 1 keeper for at least the next 5 years. Hendo will then be faced with either going back on loan, and delaying the decision for another 12 months or getting a transfer.
Hendo is 21 and can play until he is 33, so look at the next 12 years as four periods of 3 years. Forming, storming, norming & performing. He's currently in the formative part of his career, and it is vital he gets 1st team football, in relatively big games, in front to relativity big crowds, at a decent standard and decent level of pressure. By the time he is 25 be a premier league player, by the time he is 28 be a full england international & maintain that level of performance until 33. I would suggest that he isn't premier league standard yet, and the sensible thing would be for us to have him for either a 2nd season or take him on a permanent with the understanding that if we aren't in the prem by the start of the 20/21 season, he can go to someone who is. Look at Harry Maguire as an example.