The first seasons were a charm for Arne Slot and Hansi Flick. I believe the season seasons will be harder for them as most of the focus on the tactics will be on them by the opponents. I say this because I have seen it happen before.
Defending the Champion's League is no easy thing, and PSG will face it rough as well. I am not sure how Real Madrid will perform under Xabi, but I think Manchester City will still be “not so scary”.
If I'm not mistaken, no one except Real Madrid has been able to defend the Champions League title, so it won't be a surprise if PSG can't either.
Next season PSG's main rivals will be stronger, so their chances will be smaller. As for City, I agree that their golden age is over and even if they are better next season (it's hard to be worse, really) they will be in the second tier of contenders, but not in the first.