I think PSG winning the champions league they are now well motivated than ever, and next season for them would be when they give more to see if they can recreate that championship again. So they are a team to watch and definitely a favourite in the list of next season's UCL possible winners. No doubt othe teams are improving their squad depth with the transfer window open but I'm football a lot of unexpected events has always happened. And PSG can be one of such again even though it's not certain.
PSG's motivation will indeed continue to increase after successfully coming out as champions and maybe in the future they will try to maintain consistency in order to maintain the opportunity to defend the Champions League trophy. But if we talk about competition, maybe next season will be much more competitive so PSG themselves will certainly get much more difficult resistance. PSG can still be one of the strong clubs next season but I doubt their ability to defend the trophy because remembering the competition in the Champions League is not easy because there are many teams who may have evaluated the level of weaknesses that will be perfected.
PSG is a strong team but because this is the Champions League we certainly know that not many teams can defend the trophy in a row. This is a different competition from any other competition, maybe in Domestic PSG is used to doing it many times but in UCL I am not sure, because the title fight is not just about performance but many factors that each team must have. The first trophy is good enough to motivate PSG to stay focused but that does not mean they underestimate other teams who are preparing for the UCL next season.