A few points of clarification:
If there is any chess governing body that is widely recognized in the press as "FIDE" I will go with the champion recognized by that body.
If there is no such body, I will go with the recognition of whatever body is widely recognized in the press as the most dominant chess body of the time.
"most" and "widely recognized in the press" is to be supported by news articles and such, but is ultimately up to my judgement. If you want updates on how this is shaping up let me know and I will try to clarify.
If there is no such individual at all, then I will resolve N/A.
I will also not bet, to avoid ambiguity over which recognition counts becoming a problem.
I will ask some clarifying questions now so we don't have to do them in 202x:
If FIDE ceases to exist, transitions, merges, or is overtaken by another body before 2029, will you stick with FIDE or use whatever the dominant body of the time is?
If there are two of these from competing bodies....
If there is "no one" who is world champion at the time of resolution, will you resolve to the most recent one, or some other answer?