There are a lot of probabilities in your post! 
But you seem to forget that it all depends on the draws for the quarterfinals round. If PSG were to play against Real Madrid or Manchester City, I think that would be the end of their Champions League story for this season. But if they advance to the next round and then play against Dortmund or Eindhoven, I think PSG still has a chance to advance to the semifinals. There is Napoli vs. Barcelona, both teams are not that strong either and I think PSG would have a chance against them.
So after all we got to wait what the next round would be looking like, but I agree that against most of the possible opponents PSG would probably be in trouble.
Yes, you are right, it all depends on who PSG opponent is in the quarter-finals because in that round it will determine whether they can qualify for the semi-finals because if they get stronger opponents like the club you mentioned, it is possible that PSG will not be able to have a chance to qualify for the next rounds. But you seem to forget that it all depends on the draws for the quarterfinals round. If PSG were to play against Real Madrid or Manchester City, I think that would be the end of their Champions League story for this season. But if they advance to the next round and then play against Dortmund or Eindhoven, I think PSG still has a chance to advance to the semifinals. There is Napoli vs. Barcelona, both teams are not that strong either and I think PSG would have a chance against them.
So after all we got to wait what the next round would be looking like, but I agree that against most of the possible opponents PSG would probably be in trouble.
All of us here can only speculate freely and I just want to see PSG get an equal opponent, for example Napoli or Barcelona so that PSG can advance to the semi-finals.
But I'm not sure if PSG is able to qualify for the semi-finals, whether this club will be able to qualify again because Real Madrid and Manchester City have already been confirmed to qualify for the semi-finals, so at least PSG will meet a stronger club and fail to continue the match final.
Everything I say is just a temporary prediction and we all know that football always gives surprises and we don't know what surprises will be in the next match I definitely still want to see Manchester City become title holders again.
I hope that not too many of these mediocre teams get through to the quarterfinals or semifinals. I know that some will say there are no mediocre teams when they actually manage to advance to the next round and there is some truth to that, but I doubt that any of those teams that are not favorites would be as good as Inter Milan became last season. Inter went unnoticed for quite some time and for me the big aha effect happened in the final when they were close to beating Manchester City. That is the reason why in my opinion Inter Milan is one of the favorites this season. They are validating this status by their performance in the Serie A. It would be amazing to see a revival of the final of last season: Manchester City - Inter Milan. Not joking here, it would be fun.