In football there are sometimes that loses are bound to happen and despite the fact that PSG lost that game go Chelsea doesn't necessarily mean that they will be lose in their game in league 1 because with the quality and standard of that team I don't think any other team can actually challenge them for the league 1 title because they will be winners at the end of the season again and besides lille and Monaco aren't actually big team to give PSG headache.
PSG is not worried about the Ligue 1 title at all. There is no squad in Ligue 1 yet that can challenge PSG for the title. Ligue 1 teams are relatively weak. Clubs are also not very rich that they can spend a large amount of money on squad formation. So PSG can easily win the Ligue 1 title next season.
PSG lost to Chelsea in the FIFA Club World Cup. However, in every match before that, we have seen PSG players play well. Especially PSG has won memorable victories against teams like Bayern Munich and Real Madrid. Luis Enrique will definitely identify the weaknesses of his squad. There is still enough time to strengthen the team. There is no doubt that PSG will compete fiercely for the Champions League title next season as well.