Paul Pogba's injury is a big blow to Juventus. This is one of the consequences of over depending on a particular player. Now the club has to look for an emergency substitute. He is desperate to feature in this world cup because this might be his last shot, hence he is willing to take any risk. He promised to make Manchester United regret letting him go.
In the short term maybe he can't immediately play in a series A match, but I don't think it's a big loss. Juventus have plenty of stock midfielders with the same position as Pogba.
Their losses may not yet be able to get Pogba to play together and adapt in the pattern of the game. I heard he would heal a month or two. So the hope of playing in the world cup is still open. Hopefully, he will recover quickly and be able to join the French.