When compared to the previous season, I think Juventus' position is much better this season. I think it is impossible to fire Allegri just because he failed to get the title or second place. After failing to qualify for the Champions League last season, I think this is a good achievement for Juventus this season. And as you said I think Juventus will have to bring in some other players to face the competition next season. Playing in the Champions League and Serie A will be tiring and if they play inconsistently like this season then it will be very difficult for them.
Seria A flows well for elite teams that have been nothing but focused on the scudetto in the early starts of the season. Juventus headcoach, Massimiliano Allegri is doing his best to ensure things just work fine and smooth for Juventus. I know it's been really a hits for Juventus to make it up for the UEFA Champions League spot for next season. The Old lady's have been in deep struggle to win matches consistently and also missing out on their key players, all these contributed to their decline in performance.
Overall, Juventus played well but was not satisfactory, because they experienced something unexpected at the end of the season, namely they lost consistency so they didn't look good. However, with their success in the Champions League next season it is still something good for them. Even if they don't lose consistency, maybe now they can still compete with Inter Milan, because initially they had a fairly close point gap with Inter Milan.
I think Allegri still deserves to be given the opportunity to manage Juventus next season, because overall they are not bad. Maybe there is still a lot to improve, and they can do that in this season's break. Allegri has done the best he can, but things like this are not easy to predict where the club will experience a decline in performance. Next season they can improve this and prepare as well as possible to be able to play better than this season to be able to fight for the Scudetto title next season.