If Napoli will win the serie-a championship is still unpredicted, but I think their winning this season can be a motivation to try their best again to win the Championship next season. When a team wins it always affect them in a way to go back the same winning circle.
The Serie A league title is very open and can be challenged by any of the teams (whoever is serious amongst them haha). For me; its looking unlikely for Napoli to retain the Scudetto title; with a new coach coming onboard and not a quality improvement to their squad depth; its looking unrealistic.
None the less; i expect another tight title race in the Serie A this season.