The parts I talked about are more the groundwork of analyzing the here and now, rather than actually talking about it, yes. I was addressing the points about individualism and self-serving 'nature', to point out they were only capable of manifesting through feudalism, capitalism, etc., and aren't some inherent immutable human nature. We know that egalitarian societies have been workable worldwide, it's not some utopian idealist dream.

As for no-one coming up with workable alternatives, yes and no:

• There are examples of societies today which are anarchist and/or socialist instead of capitalist such as the Zapatista territories in Mexico (pop. ~300,000). Most of them are smaller pre-industrial societies, so we can't just transplant their society structure into modern cities and expect it to work, but they're still useful examples.
• The PRC presents one interesting example of dirigisme. Their state does not (nor claims to) depart from the capitalist mode of production, but it has departed enough from capitalism as-we-know-it due to the unusual power the government has over big business. So while the government has historically had troubles with corruption (which the CIA would exploit to accelerate assets into higher positions, pay-to-win IRL), on the other hand, we see institutional attacks against corrupt billionaires and selfish bosses which are unthinkable to most other capitalist states. Musk, Bezos or Zuckerburg would have to stand in the middle of Fifth Avenue and shoot somebody before they maybe go to a special upscale jail or house arrest, while the PRC have given suspended death sentences for extreme financial crimes (like Liu Liange taking millions of dollars in bribes) and notoriously executed multiple billionaires (for murder convictions).

Now, whether that second example is a society that people want, that's obviously a hotly debated topic, but I'd say objectively their system is working (in terms of stability and economic strength) and a modern alternative to our current system (their system is capable of rewarding societal values above self-service)