PSG were once very desperate to win the Champions League trophy, and now they have it, and I think that has definitely made their mentality even stronger, so I think they do have a chance to go back to back next season. It certainly won't be easy because the other big teams will definitely be making more thorough preparations (especially Real Madrid and Liverpool who are currently very active in the transfer market), but that doesn't mean PSG can't win it back because in football anything can happen.
They managed to win the title last season but it's not easy to form a mentality in the Champions League even though they have won it because before we tried to compare Real Madrid with PSG then I can say it's completely different. Real Madrid have been so dominant in the Champions League that comparing a club like PSG with them is completely irrelevant. PSG will definitely be better after winning the Champions League but defending the title for two seasons in a row is not easy and I believe next season will be much more competitive.