I see impossible to see Napoli being champion of the SerieA back to back, they never do something like that plus Inter needs to win something asap after losing it all in the end of the last season.
This plus this Napoli seems to be the best one and when this kind of teams are in that particular position they start to fall.
Napoli never won a scudetto back to back simply because they only won Serie A four times in their entire history but we can't say that it's impossible just because history says so. For me Napoli and Inter have exactly the same possibility to win the Serie A, it's literally 50/50 in my opinion. And Napoli know they have to get more players because they are going to play more matches, and it's exactly what they are doing.