Emre Can Should change the team because he is very potential and strong in the midfield, I think he is not in the Sarri's game plan anymore but he has played a wonderful game in the international level, If he moves Manchester United then it will be useful for both of them. In the squad of old lady, some more potential players are on the bench, I believe Sarri will choose Aron Ramsey and Pjanic First and then Douglas Costa and Rabbiot will play as their substitute, so there is no chance to make a start for Emre, It's a not big issue for Juve but it's major concern for Emre because he is now 28 only, He has a lot of things given towards the future
Sarri will most likely focus on two formations this season:
4-3-3 with Douglas Costa on the wing or 4-3-1-2 with Ramsey playing behind the strikers. This will depend mostly on the opposition and availability of players.
The issue with Emre Can is a complex one. Can was not included in the Champions League squad of Juventus and he felt like he was betrayed by the club. He made a bad media outburst stating that he was promised Champions League football and that he had an offer during the summer from PSG that he rejected because of Juventus. I believe that he hasn't played that much because he is being silently punished by the club because of his criticism.
Had he been a bit smarter it would have been much better for him.
Can was not included in the CL squad because Giorgio Chiellini was seriously injured and will miss most of the season. Another defender needed to take his place and Rugani did that pushing Can out of the list. UEFA also states that a number of domestic and homegrown players need to be part of the CL squad. Chiellini being an Italian was one of them, because of his injury another Italian was needed to take his place - Rugani. That is why Can was sacrificed.