I assume it has been a very long time since we last saw an Italian team in the Champions League finale. Now there is a huge chance for watching an Italian team there and that team are most likely to be Napoli of course.
There are 3 Italian teams in the current round, so it is true that the chance to see one of them in the final round is very high. I guess 2 of the Italian teams will be in the next round (semi-final). Napoli and Inter look strong enough to defeat their opponents, I assume these teams will have a chance to go to the final round. But the favorite team to play in the final should be Napoli.
We still don't know about what they can do against a tournament favourite like Manchester City, Real Madrid or Bayern Munich.
Napoli won't face Man City and Bayern Munich, one of these teams will be eliminated in the current round. But I think Napoli should have a chance to win against Man City or Bayern Munich. As long as Napoli can maintain their good performance, they even can win the title of UCL competition. Personally, I think the strongest opponent is Real Madrid if Real Madrid plays with a full team.
Even though Napoli happens to play against Manchester City or Bayern Munich as you talked about, Napoli has got a very good team this season and they can stand and beat any big tram if they should come against them right now. Napoli team has already won the Italian League so good a thing they won't been under pressure or suffer much injury crises. The favourite in the Champions League is Napoli and there's nothing stopping them from winning it.