Sergey Milinkovic-Savic is a rumoured player to sign for Juventus these days. Pogba has got injured so they need to sign a new midfielder. Milinkovic-Savic would be one of the best alternatives for Pogba and he might even perform better than Pogba when he is back from his injury. Lazio's demand would be really high from them but I don't think that they would care about that much. Their finance is very well and they can afford him easily if they want to.
Pogba injury is indeed quite detrimental to Juventus, especially since the league will start soon in the next few days, so of course Juventus will be very burdened without a capable midfielder in their midfield, but in my opinion Juventus still have a central midfield stock at this time and maybe Juventus can making it an alternative if not getting another potential midfielder, as far as I know Juventus still have Rabiot currently in their squad and of course Allegri can use him as a substitute for pogba in the meantime.