I believe there is no reason for not giving Napoli a high chance to win another championship in the Serie A next season. They still have Conte and he has built a really good chemistry the players already.
Who can prevent this potential back-to-back title? I still see Inter as the closest one to that despite bringing an questionable coach to the team. Milan and Roma have made really nice coach signings so I'm curious about what they will do as well.
Conte has managed to polish the Napoli squad to be stronger and more compact. even though they were left by two of their key players last season, namely Osimhen and kvaratskhelia and so far the gap has been filled by other players who were able to lead them to become champions last season. Next season their quality will not fade, Conte with Lukaku and Kevin de Bruyne will make them more enthusiastic to defend the scudetto from existing competitors.
For the closest competing teams, of course Juventus, Inter Milan or AC Milan will disrupt Napoli's progress in defending the title. However, I see AC Milan has a greater chance because AC Milan will not compete in Europe next season so their focus is only on Serie A. Moreover, with the arrival of a new coach who will make them able to change their course to be better to compete again at the top of the standings.