The demand signals never allocated the resources, a small number of people always did. Those people react to the demand signals (and they still do).
IMO a more important question is: what happens when the market power of a segment of society grows much greater than the rest? In a "K-shaped" economy, the top 20% have so much spending power (and even more future spending power) than their demand signals can overwhelm the rest. Then IMO the market won't respond to the demand signals of the bottom 20% and capitalism stops working for all. Add to that the possibility of AI automating more and more work and you have a system that only works for folks at the tops.
This isn't a resource allocation problem! it's a purchasing power distribution problem.
If you in the top part of the K, this is a feature not a problem.
Demand doesnt allocate resources... price and expected economic profit does.
Thats literally how the whole economic system functions.
This doesn’t strike me as a problem. There are sufficient entrepreneurs that market need common to a total 20% of the population will be met. In the USA that 70 million is a sufficiently large number. After all, that’s $700 million of MRR at $10/month.
The things limiting provision of services are physical limits like the audience being widely dispersed or just characteristics like not all sharing the same needs and therefore not actually being addressable.
You obviously are well aware that addressability does not track with income category automatically but it does for many businesses. E.g. payday loans, rent to own, check cashing, dollar stores.
Since a large section of this group is in use of government credits, at the least businesses will evolve to meet the use of those. EBT grocers, Medicaid-focused care, etc.
The majority of the effort will be spent where the greatest economic opportunity is, but entrepreneurs will match their ability to address the market to their audience. It’s not possible for a dollar store to sell GPUs to Baseten. They don’t have the capability to do something useful there.