Not that easy bro. I already made a math analysis similar with yours, last week here my posts. Because, team performance week by week will be different, so if you say 4-5 milan and napoli getting lose, how juventus can guarantee will never lose to race for this gap? Draw and lose will also can be happens to Juventus, right. And still, we will see juventus will find it difficult to manage current gap with Napoli, as you say it can be never change everything in the table.
Everyone know Napoli performance after mid season break, they are mostly getting struggle. This is the real chance for Milan or even Juventus it it happens once again. As far as Milan and Juventus can be perform better while Naples getting worst, maybe we can see the competition more interesting between top 3. For me, if Milan can't get the title this season, hopefully Napoli can manage their performance till end of season. I'm bored to see juventus dominated the title
so the main point is now Napoli, AC milan and juventus have a chance to win the title this season but the 70% chance belongs to Napoli.
I think it is more decisive to not lose the games that are not against Napoli because that is when Napoli takes advantage of others having a weak day. They just don't have very many weak days this season but if they do, the closest competitors must score the full three points. I do believe that Napoli will have a weaker day here or there and then it comes down to whether or not Milan or Juventus do their homework.
This season has been phenomena so far and of course, if they keep like that you can't stop them anyway. The only thing you can do is to constantly keep up the pressure and win all the other games until there is the showdown against them.