Having seen him 5 games now i dont think he should stay beyond his loan
It'll come down to if Ten Hag thinks Martial is a perma-crock and what the offers for him are, I'd imagine. They're in a battle to be the backup 9 and Weghorst has durability on his side, while Martial has talent.
As for this year, the absolute optimal scenario is probably still Sancho getting hot at LW and producing Dortmund form and Rashford up top and the threat in behind gives the midfield more space to operate and Sabitzer and Bruno start scoring goals centrally more from cutbacks with Rashford running wide more. Shaw's crossing, passing and shooting is good enough on the left that ending up like this in attacks still looks like everyone is in their optimal place on the pitch.
------------Rashford----------------------
-------Sancho-----------Bruno-------Antony
Shaw--------Sabitzer--------Dalot----------
------------------Casemiro-----------------
----------Lisandro--------Varane-------------
Not a lot of physicality but the ball should move quickly and creatively and again Rashford's pace should scare teams into giving us room.