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Who really needs the "middle class"? Their only function is to consume. Many if not most business is to sell to consumers. And that is the "middle" class. For example, realistically the "community college" proposal is simply a place to warehouse unemployed youth. When they get out of school, they will need to be warehoused with some type of fake job, or the system will derail.
It is a huge question but I don't expect it to be addressed in a serious way. The most likely outcome is that we will have a larger and larger percentage of the economy doing "fake" work that contributes nothing to actual productivity. "hampster wheel" jobs.
The solutions I would prefer, such as a combination of eugenic incentives, citizen's dividend, and a buyout of existing non-productive work (paying bureaucrats to retire and not rehiring for their position) to make the economy more efficient is not feasible, at least within a democracy. China, which has a favorable attitude towards improving their average intelligence, may get an advantage in this area.