I think what you're saying makes sense, considering anything can happen during a match. Speaking of PSG as the winner of the trophy in the previous season, it is very realistic if they have the desire to defend the title, but PSG must realize that the competition will become even more fierce, all clubs must be preparing their best players to fight for the top of the standings and the title.
PSG aware about that and they keep make their squad even stronger. They keep sign the new players and fix their loopholes in order to defend their UCL title. There is nothing to feel worry about.
Enrique knows very well what he shall do to prepare his club to face another difficult season. Also they will have so many players being returned from loan.
The odds is not favoring them back to back champion, but i believe they're still capable enough.
Their performance in CWC is also a very strong evidence how they're ready to face next season.