Bookmakers estimate the teams' odds exactly this way: Napoli is the favorite, Inter is the second favorite.
Napoli - 2.63
Inter - 3.75
Juventus - 6.00
Ac Milan - 6.50
As Roma - 11.00
The other teams have significantly smaller chances. But still, the main favorite has chances significantly smaller than even 50%, something around 35%, so we can assume that the season will be exciting again and the intrigue will remain until the last rounds. I wonder if Roma can displace anyone from the top 4? Of the "other" teams, they look the most promising.
This season promises to be exciting and I say that because of how much improvements I have seen from sides like Roma and AC Milan but my support stays with Napoli, I think they have a better squad now than they had last season. If they could win the league title with the squad they had then I believe they can defend the title this season.