Napoli can become a champion again, but they have to beat all of the big teams. Napoli has to get more than 85 points at least to win the competition. This can only be achieved when they able to take three points from all of big clubs. If they were not able doing it, they won't win the competition.
It's hard to guess which club to win the title this season caused by all of big clubs are equal right now. The odds is not favoring Napoli, though they is topping the league now.
Napoli has good quality indeed this season under Conte's guidance but Atalanta, Inter Milan, Lazio and also several other teams currently also have sufficient strength so that the competition will be even more difficult this season.
To be able to become a champion requires consistency, it is very difficult especially since this season's journey is still very long so anything is possible for the top teams at this time but one thing is for sure that the competition this season will be fiercer than last season.