In terms of our plan A, I think pretty soon it will be Rashford-Martial-Greenwood as the main front 3. James will be rotating on the wings when necessary, and that's pretty good right there. The problem is we have nobody to change games for us up top. Hard to count Rashford or Greenwood as backup strikers when they'll be starters in the wide positions. So we definitely need a bench/rotation striker to make a group of 5 attackers for those front 3 positions.
Ideally, would want that player to be like a Dzeko. Someone who is excellent technically and at holding up the ball, provides an aerial threat, is focused on scoring goals. Not many of those around, and it's probably better to try and get someone in their late 20's/early 30s to be that option.