If we sign Sanchez, I think we still need a #10/AM/CM that can create something in order to keep us overly relying on Pogba.
Pogba is and will be our best midfielder, so I don't expect us to go buy a Pogba v.2, but when Pogba is out or needs a rest we should have a creator to play either in midfield or at the 10 so our "penetrating attackers" can actually be fed to some extent. Rashford, Sanchez, Martial and even Lukaku has pace to run in behind and counter-attack, but only Sanchez and Martial will be able to create on their own.
I believe Mourinho agrees with this, and that is why we're reportedly interested in Özil. Because despite him being a "luxury" player, he's a creator we can get on a free that can do that job when Pogba is out.
I do believe that us getting Sanchez ends our run at Griezmann due to Griezmann being another player needing to be fed, but I believe it opens us up to buying a different kind of player, a more creative kind like for example Dybala (assumptions based on what I've read, not what I've seen).
Not that I believe we'll sign Dybala, I still believe we'll go for Özil in order to have more money to spend on upgrades elsewhere (mainly LB, RB & potentially CB).