correct mi if im wrong but squad wise, we only have 2 Club home grown players in Miretti and Savona (and Rouhi but he is leaving), so we can have maximum of 23 players in the squad (not counting Adzic and Yildiz who are U22):
1 Michele Di Gregorio HG
2 Mattia Perin HG
3 Carlo Pinsoglio HG
4 Bremer
5 Pierre Kalulu
6 Federico Gatti HG
7 Lloyd Kelly
8 Daniele Rugani HG
9 Facundo González
10 Andrea Cambiaso HG
11 Juan Cabal
12 Jonas Rouhi CHG
13 Nicolò Savona CHG
14 João Mário
15 Manuel Locatelli
16 Khéphren Thuram
17 Weston McKennie
18 Fabio Miretti CHG
19 Filip Kostić
20 Teun Koopmeiners
21 Francisco Conceição
22 Jonathan David
23 Dušan Vlahović
24 Milik
Vasilije Adžić U22
Kenan Yıldız U22
So IF we get rid of Nico, Djalo, Arthur and Rouhi we actually have place for two players in the squad. Im not counting guys like Facundo Gonzalez and Milik since they would be sent to U23 anyway probably.
We could get Kolo and Zhegrova if we sell Nico, since all the rest seem to be easy to sell.
With Vlaho departure we could have a look at another signing.