It's obvious that they wouldn't be able to achieve similar performance next year, because Chelsea have shown other clubs PSG flaws. For Chelsea to humiliate PSG in such a shameful way, it means that PSG is no longer the strongest. They can win Ligue 1 as many times as they want but not UCL.
Even though it was PSG that defeated Chelsea in the Club World Cup final, it's not certain PSG will win the UEFA Champions League trophy next season because the UEFA Champions League competition is a difficult competition for a team to win the trophy back-to-back. PSG has no rival for the Ligue 1 title; they will win it before the next season ends.