Last summer, Juve turned down two very big offers. Now Pogba is a rising world class player and Juventus is a big enough club to keep him for a long time. That's why he signed a new contract there, but keeping a star is a difficult thing. I'm not really talking about Juve, but about the Serie A.
He's a true profesional. I see in him the same qualities I saw in Ibra and nedved: his mental, a strong body, a real talent, a self-sacrifice. He will win more than one Ballon d'Or. If he has a fee? No. You can't put a price on him. That's the role of the ones who want to buy him to do it.
As of today, he's the most expensive player in the world. His relationship with his club is excellent at the moment... Well at least till another club put an offer on the table.