Only Real Madrid has won the Champions League back-to-back. PSG can also try to create another record for themselves next season by defending the title, but I don't that's possible because they would still be carried away with the excitement of being the defending champion and might lose focus on taking their matches seriously like they did this season.
The rest of the teams will not make the same mistake every time. At the beginning, PSG was not a very strong team, at one point it seemed that they might be eliminated from the group stage. But they managed to extend the elimination period much longer and finished the Champions League with the title. Our expectations were around Real Madrid, Arsenal, Liverpool or Barcelona. But those expectations were not met at all and Inter Milan and PSG entered the final from outside the expectations. Here, of course, the fate of the two teams worked, because the mentioned teams were stronger than them. But maybe this will not happen again and the mentioned teams will not make the same mistake next time.