Joking aside, as long as PSG keep up the good work it won't really be easy to prevent them from a back-to-back title.
I don't think they will lift a back-to-back title. That is too much to ask. After getting exposed by Chelsea, wait and see how teams will come at PSG this coming season. That fear factor they had is now gone!
We'll just have to see what steps PSG will take next. Despite their status as the reigning champions, defending the Champions League trophy isn't easy. Even after Real Madrid won three consecutive Champions League titles from 2015 to 2018, no one has managed to do it (back-to-back). Even in the final, it's sometimes just the same few clubs, but it's certainly difficult.
The coming season will be similar. The Champions League sometimes presents some surprises that are difficult to anticipate. Furthermore, the competition is clearly a bit tough because it's a competition where the best clubs from each domestic league come together, so ultimately, it will certainly be a tough task to complete back-to-back matches.
However, I think Enrique will continue to give his best. Their momentum hasn't faded, even though the CWC final didn't go as expected. However, their spirit is still strong enough to continue their consistent performance.