Second, capitalism can be replaced in a free society if a superior model is introduced. No one is stopping people from starting up worker cooperatives, communes or non-profit organizations.

By all means try to replace enterprises that are motivated by remuneration, but don't do it by violating people's right to freely contract. Do it by making a better model that people freely choose to switch to.

Funny how HN comments are so full of complaints about practices that inhibit businesses our system is actually designed for. What makes coops and communes so easy?

Communist Manifesto isn’t a work anyone seriously defends. Marx didn’t even defend it. It’s a history scrap; significant by contextual events. If you read Marx’s seminal work, you’d not honestly raise such a moot point.

Insofar as there are obstacles to starting businesses, communes, etc, they are a result of interventions by the state that inhibit the free market, like permitting and licensing requirements, so the solution there is to go more toward a free market, not less.

>>Marx didn’t even defend it.

That's extremely disingenuous. He authored it. He titled it 'The Communist Manifesto', thus placing it at the center of his political platform.

That is; a society, and a social contract.

Your basic “apple-for-a-dollar” trading will always be around, sure.

But billionaires and massive wealth concentration are a thing that can only exist if society is structured to allow it.

Trade and markets might be, absent of all outside interference (I don't think this is even possible), but capitalism has definitions that go well beyond that.

Capitalism isn't going away I don't think, but rather the reverse. However it could be managed a bit better.