EtH is a very detail oriented individual and will absorb any and all insight when it comes to players. And he already has analyzed the current squad, it is obvious by his preparation and understand of how he thinks he'll take the club forward.
This includes Marcus. And this could include the unfiltered insights that Fletcher and Rangnick have experienced for almost 5+ months now. Marcus complained about not getting enough time on the pitch, which Rangnick easily disputed to the media. And has continuously lost a starting position to either Elanga, Sancho, or Pogba. It's a damning indictment on Marcus the football player.
People talk about Murtough about being this or that. Well the "Ole's first real test" joke has applied to Murtough about EtH or Poch. He chose EtH. Now another one will be Rashford - stick or twist. Going into the 22/23 season, Marcus will only have one additional contracted year with the club (23/24). Murtough and the club should sit on Rashford and continue to give him all the time needs to be a player for this club as he's still under contract. Make it up to him to perform and compete for a squad position, knowing there is 5 subs starting next year in PL.
Marcus is free to explore opportunities outside the club in Summer, as all players are. But I just really, really hope that the club do not extend his contract within the next year. Let him see out the next season because he, like nobody else, is a guaranteed starter with EtH. But with Sancho, Elanga, and at least one new wide forward and one center forward being scouted (e.g. Antony, Nunez), there will be competition for places.
If Marcus doesn't want to step up to the challenge and really compete and fight for a starting position or embrace an impact sub role, then he's going to be out of the club. It is up to him, as it always has been.