I think Januzaj would probably benefit from a loan also because i do not think on his performances he is going to push anybody out of the line-up. If he wants the number 10. position then he is contending with Rooney, Mata, Di Maria, and Van Persie. If he is played as a winger or wing-back then he is contending with Rafael, Shaw, Young, Di Maria and Valencia. And were we to play a diamond then he would still be contending with the likes of Rooney, Mata, Herrera, Di Maria and Fellaini.
Januzaj needs game time in order to gain experience and maturity but he is not going to be given that at United in bundles if he doesn't perform (which he hasn't).
A loan would do the young man good.