I think the odds of another V&M return are something extremely close to 0%. I wasnt even that surprised they came back this quad, post Sochi I would have given V&M and D&W both about 35-40% odds of returning at some point (which I guess makes roughly 60% 1 of the 2 would as happened). Not this time. They have a historic Olympic medal count now, they have met all their goals including regaining their Olympic and World golds, and winning the elusive GPF. They have competed at the top level over a decade. They have made the best possible case for themselves they could ever make of being the best dance team ever, or one of the best ever, and anyone who thinks they arent (which btw is a valid opinion, dont get me wrong there) wont ever at this point, nothing they could do from here would change anyones mind.
So in all there is absolutely zero reason to ever return now. Also when they returned this time people were excited to see them, and they were almost sentimental favorites of all, including even the judges, after ending their last run with a string of losses to Davis & White. If they returned again, no way, except for Canada. It would be more of a "why the heck are you back again now" kind of reaction. Lastly it took their best performances ever at an unlikely age to barely hold off the much younger French. And they are going to think they can return at a much more "too old" type age for dance and do it with the French having had years of improving.

Not to mention the Shibs and all the other younger teams who might continue. They might be confident, but they arent stupid. If V&M ever return to amateur at this point I will be beyond amazed, and I think even their nuttiest ubers would agree.
If P&C are to be challenged/beaten or even denied the OGM again it wont be from V&M, that is for sure.
As for Zagitova, even if she surprises me and continues past this season at all (that would already legit surprised me as I explained why) I will be amazed if she competes all the way through the next Olympics, never mind dominates all the way through to the next Olympics. Not nearly as amazed as a V&M return mind you, but still really surprised. That isnt hating, it is based on some very clear evidence. If she even competes say another 2 seasons and retires she will already have majorly bucked a trend for female OGM winners.
Hanyu I would also be really surprised if he even tried to compete to the next Olympics (although ironically less than the much younger Zagitova just since the mens precedent is pretty different than the womens) although I could see him go another 2 years quite possibly, but not for an entire quad now that he has his 2nd OGM already imparticular.