Currently, Napoli is struggling in 5th position with the same points as Fiorentina. Napoli is having difficulty breaking into the Champions League zone because the stability of their performance is the most obvious problem at the moment, of course because they tend to lose more points. Until week 16, Napoli had suffered 5 defeats and 3 draws in 16 matches. So in my opinion, Napoli will not defend their title and will probably just struggle to qualify for the Champions League next season.
Yes, currently Napoli is struggling to occupy the top 4 position so that next season Napoli can compete again in the Champions League but it seems that Napoli is having difficulty reaching the top 4 with its unstable performance while Fiorentina and Bologna are also try hard to enter the same ranking, we'll see just whether Napoli can occupy the top 4 position with his current condition, maybe if Napoli is able to improve the team's performance and appear more impressive, Napoli still has a chance to occupy the top 4 position this season.