Just like the possibility of hiring Lampard feels like a PR move, sacking Sarri now would be bad for PR as well (although we have sacked managers just weeks/months after they won a trophy before). So as you said, it might come down to whether he wants to go to Juventus.
My main issue, if he does stay, is the transfer ban potentially sticking. Today is apparently the last day to appeal to CAS and we haven't heard anything about it. If we can't sign any players that would suit Sarri's style, then does that mean we are in for more tedious football next season? Are we going to see all the struggles, inconsistencies from this season again in 2019/20? Can he develop and integrate the young players into the team next season? Based on this season, I'm not entirely convinced because he only seemed to really use CHO and Loftus-Cheek after all the calls from fans and media started and there's also the fact that he was sending mixed messages over CHO after the Bayern interest came in. Am fine with (another?) transition season in 2019/20 if he develops the younger players, make us play better and more consistent, show progress with the team but am just not all that convinced.