We'll be willing to sell for anything above 14.4m euro (we signed him for 72m on a 5 year contract, so 14.4m euro per year). But, unless he signed a new contract with us that I'm not aware of, this is the last year of his contract, and I guess that teams will prefer to get him on loan. I too doubt that we want to pay his salary (4.5m euro per year?).
I don't see him in Juve next year. I also don't see a team paying more than 14m euro for someone like him with a year on his contract. Hopefully the latter will happen, but tough chance. A new loan is most probable.