A midfield actually nullifies all the issues we had with Martial being out because with proper creativity in midfield even Rashford would be able to play as a CF again and Greenwood would also have an easier task there.
Right now Martial role is elevated because he tends to drop deep in midfield thus helping our inept midfield creativity(Lingard and Perreira guilty of this) thus his role becoming even more essential because he's now tasked with making things happen for other forwards/attacking players.
But once you have a good and creative midfield we can play any type of striker there, not only one that can hold up play and drop deep to help create. Therfore Rashford becomes an option again as CF and Greenwood can also be trusted in there despite his young age.
Honestly, wanting a new striker shouldn't even be a topic when we technically have 3 strikers in the squad in Martial, Greenwood and Rashford. These talks have crept in only because our lack of creativity which led to lack of goals sometimes make it seems we don't have goalscorers which isn't actually the case. Creativity is what doing us in.