I think that PSG is having a shite season and that those who were of the opinion that Ibra and Blanc carried the team were probably correct, judging by the performance after they have gone. It's not like the rest of Ligue 1 has gotten stronger either.
As for your question, I think they'd need to show a level they haven't this season to beat Barca, and have to fully focus on the league to MAYBE win it. It is not a question of picking one or the other, the concept that they could fail at both is a reality right now.
What does everyone think of PSG?
Undoubtedly they are one of the best teams in Europe but they have always failed to prove themselves as they have never won the Champions League despite spending highly on new talent. This is obviously their aim, hence the reason they brought in Unai Emery who had done so well with Sevilla in the Europa League. However Emery has never had much experience and success as a coach in the knockout stages of the Champions League.
Do you think PSG will manage to focus also on the league and retain the title as well as succeed in defeating Barcelona to progress in the Champions League?