Of course it would be very interesting if Napoli could be in the Champions League final this season against Manchester City (and even if Manchester City could beat Bayern Munich and also Real Madrid) because I'm also not sure that Chelsea can hold Real Madrid from advancing to the next round because Chelsea's performance this season is not very good and also not on par with other teams who are still in the Champions League now.
If Napoli can win the game in the quarter finals, they will meet either Inter or Benfica. If Inter wins, then the semifinals, Napoli will meet with a Serie-A team again, which is more likely they are able to win against Inter. If this result is correct, then Napoli have a bigger opportunity to reach the Finals when referring to their achievements in Serie A. But, against Benfica, I think it's still waiting for the results of the 1st leg. because benfica also has good performance in the domestic league, so it's quite difficult for me to say that Napoli will beat them.
Napoli's actual condition at the moment in terms of opportunities for their final is quite large with their current position. Against Milan I think everyone pretty much agrees they are the favorites in this game.
On the other hand, for Benfica and Inter, I'm still not too sure who will win, but one thing is certain, if Napoli wins against Milan, whether it's against Inter or Benfica, their chances will still not change for this season's final.