Since just before the start of Serie A, the management's priorities seem pretty clear. 1st needed a competent workhorse CM - Matuidi. Next, needed another full back option - first link with Spinazzola (who can play both sides) and finally settling for Howedes. If he does well, we could buy him out next season. Barzagli may retire after this season and we could bring in Caldara and Spinazzola next season.
So this season: Lichsteiner, De Sciglio, Rugani, Chiellini, Barzagli, Benatia, Sandro, Howedes
Next season: Spinazzola, De Sciglio, Rugani, Caldara, Chiellini, Benatia, Howedes, Sandro - subject to change depending on performances and opportunities
As things stand, we are set after Howedes. From here, I would not be surprised if the squad stays as is.
However, if Strootman can happen (via a Cuadrado swap deal while landing Keita), then that is possible. Or Renato Sanches as a loan could be opportunistic.
My sense is that in terms of squad numbers, they want to have 8 defenders but with enough depth and versatility to play a back 3 or 4 all season long - that is achieved with Howedes. Midfield - probably 6 of good enough quality to either adopt a mid 3 or 2 all season long. My sense is that forwards? 7 is the right number where you have 3 capable as playing as strikers and the remaining as wing based forwards. Cuadrado and Costa are too similar in a way so I could see them offloading Cuadrado if the right exchange was possible.
After Howedes, I think the last transfers would happen on the last day if at all.