What you said makes sense, considering PSG journey will be more difficult than before, all clubs will prepare their players to perform more optimally in the upcoming matches. It is not impossible that PSG can be eliminated faster than imaginable, therefore they should not be complacent about the wins they have gotten before, train harder, improve coordination between players to be better, etc.
To assume PSG to be elimited earlier is totally wrong. They have totally learned their past mistake, and perform multiple times better than when they only relied upon their star players. Also, there's no a lot of changes happen in the squad. They still use same coach, same players, same management, but some new faces that may come to their squad.
That's why they still remain as one of top candidate to win UCL next season. Don't forget they have oil's money.