Solskjær is reportedly thinking of using a 4-3-3 more this coming year if Varane is signed. With Sancho's signing, I doubt that we will see as much of Pogba playing as a left-winger. My guess is that to start the year, we will see Sancho - Cavani/Martial - Greenwood as the primary front three. Cavani will get some rest to be saved for the Champions League and towards the end of the year. I think Amad will get a chance to contribute, and if he is able to do so effectively he will stick around all year. If not, he is likely to go out on loan in January. His presence at the Olympics probably dictates this as much as anything. I don't like seeing Martial on the left. I don't think he is effective on the wing, and I think he allows himself to become discouraged when playing on the wing. We might even see VDB in one of the forward positions in some matches.
Rashford will regain his place on the left, and Sancho will move to the right. Then, we might see more of Greenwood at CF.