It is true that when PSG won the UEFA Champions League trophy in the just concluded UEFA Champions League competition, nobody knew they would be the winner because PSG was an underdog. But I don't see PSG winning the UEFA Champions League trophy next season because the UEFA Champions League competition is a difficult trophy to win back-to-back. PSG will only go far in the competition, but winning the UEFA Champions League trophy in 2 consecutive seasons isn't certain.
How did you manage to get your prediction, PSG was never seen as an underdog to Inter Milan, lets get things straight who did PSG play against during quarter final and semi finals, their opponent was really the best and they thrive through those stages. I agree that PSG based on their current performance are going to find it difficult defending their Champions League title against this big clubs again, each teams are gathering their best squad for next season competitions.
Going far in the Champions League will not be a problem for PSG, Aston Villa looking classless was able to make it into one of the finals, PSG have a nice record of becoming a good contender.