#1 Versatility
As polished as they are, as much quality as they offer, it is hard to imagine United restraining themselves in the transfer market on account of Rashford and Martial. Players will inevitably be signed; presumably, ones that can come in and fire right away. It is not easy for young players in such situations, to accept bench duty while knowing that they can play every week elsewhere.
That is where the duo’s versatility could be a real blessing. Both Martial and Rashford can operate across the front line, meaning any one signing is unlikely to resign them to bench duties. Moreover, they can provide cover for all the forward positions, meaning the club would loath to lose them irrespective of incomings.
If they bide their time in this manner for a couple of years, they would by then have been ready to stake an uncompromisable claim in the first XI. Boy oh boy, that would make a fearsome sight for Premier League defences.