He's 40, how long do you want him to play? I'd love for him to come back/stay at Juve off the pitch in whatever role, but i don't want him to keep on playing forever and become our very own a Totti. It's the right time to stop playing, at least a on the highest level imo.
If he still enjoys standing on the pitch, MLS or some other retirement league would take him in a heartbeat i guess. So go there for 2 more years or so, take a break, and then come back to Juve for some administrative role.