I know there is a lot more dance material released nowadays compared to back in the '70s, but boy, does this statistic floor me.
From the UK Dance Music Resource pages:
New Releases December 9th - December 15th 2002

Singles - 524
Albums - 43

Just think how impossible it's gonna be in 25 years time, to have any sort of meaningful discussion with like minded souls. Just where would you start to find common ground? Even if there were 20 sub genres (which there aren't?), there'd still be records that could be totally unheard of. The mind boggles.