I never believed Napoli would win the Scudetto, but Napoli surprised everyone and won the Scudetto. Yes, some clubs have changed their coach, but they don't have a good squad depth to compete for the Scudetto next season. I believe Inter Milan and Napoli still remain the favourite teams to win the Scudetto next season, and it won't be a surprise if either Inter Milan or Napoli wins the Scudetto next season.
Napoli won the Seria A title because Inter Milan suffered a surprised drop in form towards the end of the season. Inter lost some points which made Antonio Conte side win the Scudetto with one point. Predicting the winner of the title next season might be difficult considering that Napoli finished in tenth position last two sessions but they become champions. So clubs like AC Milan and Juventus cannot be underated.