Ralf Rangnick wouldn't be eager to sign Pogba's replacement in January considering he's manager for just 6 months so I reckon he doesn't rate one of Fred/McTominay and my guess is McTominay.
If Rangnick wants Haidara then Man Utd should sign him. I trust my gaffer.
McTominay should be groomed to be a proper DM. He can be good at the job. The high pressing style with a poor defense will leave you conceding goals you need enough people at the back... Remember Liverpool before van dyke and fabinho? The would score 5 goals concede 3