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.
Never say never when it comes to football. If Napoli were able to win the league trophy last season tell me why it is impossible to win it this coming season with the recruitments they have made to further improve their team. I think it is very possible, their team looks very organized and stronger for next season.
Napoli will have a lot of busy schedules and that will affect their performance. Unlike, last season that they were only focused on Sera A competition. This is one of the reasons why I don't see them capable of winning the Scudetto back-to-back. Fatigue and injury will always play their own role on the players. Napoli was lucky last season that none of their key players was injured.