I'm interested in the total number of active chess clubs in the world. I'd also be keen to see any historical trends in this number over the past couple of decades.
I would imagine that the number of chess clubs remain relatively constant. From my small sample size of exposure, I have not witnessed a single chess club die out but have seen a few born. Chess is certainly not decreasing in popularity, so I don't see a reason why there would be a decrease in the number of chess clubs.
Chess organization membership rises and falls with the popularity of the game of chess. About 60% of the members in the US are youth, organized in school and college clubs. In the 1990s there was a trend of rising numbers of school clubs in the US, and the membership numbers peaked around 2002. Chess has declined a little since then, but is not 'dying off' at all. THE Google trend graph for 'chess' is down slightly:
The interest is still at a relatively high level, and factors like celebrity players could cause a resumed increase in youth interest.
Depends what you call a club. Some are big some are small. Some are formal some informal. Some are official and affiliated with FIDE or USCF or some NCF.
Your very open ended question would include anything that they themselves call a club. So counting everything that thinks they are a club then the answer is 42087. Can not be disproven. And there is no official list of them anyway so it can not be proven either.
This is very much an opinion question which some mods randomly delete but at other times they ignore.