Negative sum, all that fun hardware and hard workers live off trading commissions.
Something to think about is the market originally existed to raise capital for massive industrial projects like transcontinental railroads and Ma Bell and steel mills and factories in general.
That's methodically been destroyed and soon will be as economically relevant as selling farm tractors is today.
True its diversified out into providing capital to set up financialization schemes, holding companies, stuff like that. But in the very long run I'm not seeing a purpose in having a stock market. That would tend to make it go away.
Take America 2016 and just turn all the dials up to 20 and call predictions for 2036. The last industrial employer closed years ago so no need to raise money for factories full of workers. The last privately funded construction project was built long ago and all construction not just sports stadiums and corporate HQs are completely government funded, no need for stock market funds if all the money comes from taxpayers. Income inequality has accelerated to the point of there no longer being a consumer economy, no need to finance consumerism like retail stores or car loans by selling stock. That also means no advertising because there's almost no value left to extract once all the blood has been squeezed from the stone, which in a country where no one can afford medical care, higher ed, or housing means they don't need to sell stock because they've crashed and no longer exist for all practical purposes. Of course this sounds all rather negative but theres plenty of good news. I'll continue to front money to my local farmers for my vegetable CSA and my occasionally "half a cow" purchase... although none of that requires stocks. Now that software has eaten the world and no computers cost more than a $5 Raspberry Pi, I can work a startup at my local makerspace with practically no money and certainly no need to raise money by selling stock, capitalist industrialism was so 19th century, I don't need to sell $25K of stock to buy a Sun SunOS minicomputer to serve DNS in a world of cloud computing and $5 raspberry pis. There's no need to invest 401K funds because everyone except the hyper wealthy is dirt poor, so no financial market demand.
Yes yes the interval from 1850 to 2000 or so was an era of needing massive investment to build industrial infrastructure. And we need great piles of cash in say 2050 to build... what? Nothing, would be my guess. So the marketplace to raise great piles of cash will go away, more or less.
The future being unevenly distributed, you should be able to find a country today thats de-industrialized (or never industrialized to begin with) and has wide enough income inequality that the population has mostly gone back to barter (probably computer / smart phone assisted agent bartering, but no currency anyway). One where most of the population works non traditional jobs, more like subsistence farmers or subsistence economy in general. How about subsistence farming in Columbia, how healthy is the fraction of the Columbian stock market that focuses on or works closely with subsistence farmers? Oh there isn't one? Oh. Well that's the future of the NYSE given recent trends.