The thing is that most of us on STW are leisure/sport users seeking higher-end products from a range of businesses pandering to the must-have-latest-spec market.
Meanwhile the greater percentage of people riding bicycles in the world are likely to be riding 26" wheeled bikes, probably rim-braked. Rims, spokes, tubes & tyres in 26" flavour will be available for years to come. The worldwide market for them is just too large to ignore. It's only the high-end lightweight bling stuff that will likely fade away, probably in favour of 650.