If you believe Allegri can provide good results for Juventus, then this season Allegri should succeed in making Juventus dominate Serie A. Because after all, this season Juventus clearly only played in Serie A but in fact? Juventus even continued to decline and I don't think it's worth it for Juventus to keep Allegri. Try not to attribute success to the past, because to be a great coach ofcourse the coach will be able to maintain goodperformance and quality for the team itself. But, if you really like Allegri to stay at Juventus, I would say congratulations, because then Juventus will never be able to win trophies again.
In this season, Juventus not participants on any European tournament from Conference League until Champion League and focus domestic league only. But he failed bring Juventus keep in the tittle race and current dropping to 3rd standings position after bad result in last several matches. I don't think any success achievement for Juventus under Allegri era and he failed make Juventus keep consistent performance after success pressure Inter Milan on the top position.
Have been longer time for Juventus not winning Scudetto, I think need rotation not only with the players but also have to sack Allegri from his position after two season failure helping Juventus for winning domestic league tittle again.