Chelsea didn't want to sell him before he left so if he keeps playing well and creating hype for himself I can't see why they would change their minds.
Certainly not at a discount anyway. This loan was only possible because of two reasons.
To drive his price up or to get him more experience so that he is ready to start playing for them.
Either way this is going to be really difficult unless he plays terrible for the rest of the season.
I had a look to see what Chelsea fans were saying when he was loaned, and some were suggesting Chelsea only wanted to sell him (I'm presuming for PSR reasons) and weren't open to a loan, which several teams offered, but when Juve came in all parties were happy with it.
Supposing this is true, and I do think there is a focus at Chelsea to shuffle the pack, and may well move a fringe player for 30m+ that they paid 14m for (due to juggling PSR), my biggest concern for signing him permanently is that if he plays great we only have the will of the player in our favour, as he seems to have fitted in well. Otherwise his valuation goes up and we would end up either being outbid for him or paying over the odds (again).
He may well get promises that he'll be in the main 20 players next season, but Chelsea are very scattergun in how they assemble their squad, and many of the players feel like nothing more than investments to me. After all, he only played 176 mins so far in the league this season, and out of position.