As a Napoli fan, i think it’s going to be a fierce battle for the Scudetto this season. Napoli has brought in some really quality players, especially KDB, who, from what i’ve seen in the preseason matches, is not exactly in top form at the moment. As for Milan, i think they will take things seriously and start playing seriously. With Luka Modric, anything is possible 
Next season the battle will be between Napoli and Inter Milan for the Scudetto I don't think any other club has what it takes to challenge them in the title race, apart from KDB Napoli has other good players that would help them to defend the title and KDB will just use his experience to create good scoring chances for the Napoli strikers. Inter and AC Milan are the other two teams that are making good moves in signing players but Inter Milan is the only team that can challenge Napoli from what I can see other teams don't really have rust quality players that can stop Napoli.