I have a slightly different opinion than you. I think the Barca and Napoli pair is quite unpredictable; they are the reigning champions of both the Spanish and Italian leagues. Currently, the form of both Barca and Napoli is not good, but when they face each other, the result is hard to predict. Napoli's style of play remains challenging for teams from England and Spain. Therefore, it's not easy for Barca to overcome Napoli in this round.
When you look at the performance of this two teams, it is very obvious that they are on the same level now. Their individual performance in both leagues is just the same and nothing much can be said in their upcoming match against each other. One of this two teams will be eliminated from this round and won’t advance to the quarterfinals, the thought of it makes it more interesting to watch out for their match by next year when they meet in the round of 16.
Squad depth and experience tend to give Barcelona an edge over Napoli in the Champions League, but the teams' performances this season have been relatively similar in their respective domestic leagues. I hope that Barcelona will be able to qualify for the quarter-finals this season by beating Napoli, even if Barcelona fails to reach the semi-finals then Xavi will actually have brought the team up two levels from previous seasons in the Champions League. Of course I don't consider Barcelona capable of getting to the final and winning the title, that seems unlikely.
Napoli was the home team in the first leg, so it is possible that they could perform better than Barcelona. I don't think we can analyze what their chances will be in this match, I mean there are several things that might change it, including the availability of players in the starting line-up.