The 2025/2026 season, PSG can still be relied on but their rivals are tough. Liverpool and Real Madrid are ready to be their destroyers in defending the defending champion title.
Indeed, it will not be easy for a club to maintain their UCL title in a row, besides the three clubs you have explained, there is also Barcelona who still has the spirit to be much stronger, Napoli with their return to the top position of Serie A, and Bayern Munich, and maybe Man City (although doubtful when looking at their performance in the Club World Cup).