Playing Cesc as a false nine is not something that the midfielder would have to adjust to – he has done it plenty of times before in his career.
However, doing so would take him away from the middle of the park and diminish his ability to dictate the play and indeed tempo of the game.
Something Mourinho is unlikely to do unless things begin to go south.
However seeing the likes of Andre Schurrle or Willian deployed there might just be an option.