It will be interesting to see how Massimiliano Allegri will deal with Massimiliano Allegri. I said last season that Milan's biggest problem was in defense, in attack they were fine. The thing is that Massimiliano Allegri is an expert in defending, so if he can strengthen Milan's defense and keep Milan's attack strong then I would say Milan will have a good chance of fighting for the title.
Now I don't know how many Milan players will not leave the team and how many will be signed. Milan is lucky to have the first ones: Cremonese, Lecce, Bologna and Udinese. If they win these 4 games, and then manage to beat Napoli then they will be well on their way to fighting for the title.
It is really smart to think about how Massimiliano Allegri will impact Milan especially since he is known for strong defense. If he can make Milan defense solid without hurting their good attack they will be serious contenders for title. It is tough balance but he has experience to pull it off. Big question mark is who stays and who new players they will sign as this will hugely affect their chances.
You also pointed out good early path if Milan can win their first four easier games against Cremonese, Lecce, Bologna and Udinese and after that beat tough team Napoli it would really show they are ready to fight for championship. It will be exciting to see how it plays out.