Only Real Madrid have been able to win the Champions League back to back. Apart from them no other club has done it. This is why I don't think that PSG can defend the title because they cannot be in the same form like last season. Many clubs have improved their performance by by additional players to strengthen the team. I believe that PSG will find it difficult to win some big teams that they defeated last season.
I would have loved to see a different club entirely winning the title this season.
Manchester City has won the champions league at close intervals too, Real Madrid mostly won the champions league in a row when they had Ancelotti as their coach but now he is no longer with them so it is possible an erra of a certain history is ending so never say never even when we know PSG lacks the capacity to defend the champions league, they could just gwt lucky in an unusual way and end up winning in a way we do not expect they would.