I think the government will be incentivizing stock ownership much more via state sponsored 401k, or HSAs, or 529, etc. Even now, we're only at just above 50% of population having a stake in public companies:

https://www.chicagotribune.com/business/ct-americans-dow-220...

Also, number of public companies is decreasing, with the bigger players getting bigger and bigger. And finally, I would expect even more international funds to flow in to the large conglomerates as their efficiencies of scale take over.