He always played with 4 at back i doubt he'll change that, plus Cancelo and Spinazzola are amazing as winger in a 4 mid and we are selling them, so no 3-5-2 or 3-4-3.
For the rest we have to wait, if somehow we sign Isco then 4-3-1-2 is totally possible, if we sign Icardi he'll play CF and...