He's not a winger so he'll be in contention for the same roles as Rooney, Mata, Januzaj, Lingard, Andreas Pereira: #10-a-like. Not the player United most need. How about we buy a fast right winger who can cross and go past their man, or a taller-footballing-left centre-back, or Carrick's replacement, or a fabulously expensive 40 goal/season forward. I already think Rashford is a 25+ goal/season forward.
Right now he is the clear winner with these options. If mourinho comes no way he will play pereira and mostly won't play januzaj too. Mata already has been sold by him once so it won't be surprising if he did that again.