No, I don't think PSG has a big chance of qualifying for the final next season. There are not many teams that can play in consecutive finals in different seasons and as far as I know one of them is only Real Madrid. PSG are no longer favorites for next season's final and I tend to agree that the team that does not qualify for this season's final will actually go to next season's final.
I think it is not the right time to judge PSG that they will fail to reach the final in the next season. IMO, it is not something impossible to reach the final again, Real Madrid has proven it. Well, I think we don't underestimate PSG, it is not the same as PSG few years ago. PSG has become a winning team, they even won 3 major trophies. Considering the quality of PSG squad now, it is quite possible that they can compete for the title again in UCL next season.
It is very difficult to maintain a team's performance over many seasons. The main players will not always be available in all matches for various reasons. Injuries, international matches or suspensions may have an impact on the team's performance, so consistent performance is very difficult for whoever the coach is to maintain.
Sure, it is something difficult to do. But it is not totally impossible as long as there is no big change in the team. If you take a look at PSG, you should realize that there is no change in their main squad. So we can expect that they still can show their good performance constantly in the next season.