Capitalism defeated communism because capitalism better aligned rewards and work, so that people in capitalist countries worked harder. Jobs in the USSR were like social clubs and not much actual work went on, because you wouldn't be rewarded even if you did work.

The economic system that causes people to work harder will win. To be a challenger to capitalism you need to be serious about getting people to work, and not dream about a society where 90% of people are in the leisure class. Such a society would be defeated by capitalism again.

So how do you get people to work? Such a system must respect private property rights. You're DOA if you don't.

The main flaw in capitalism is in the name: it's a legal system that favors capital. Given that the holders of capital are few, this is a massive market distortion. What is an "undistorted" market? If your cost function is getting more people to work so that your society is more efficacious, and we know that most people are in the middle along whatever dimension you measure, then a system that favors the middle - because that's where the people are - rather than the right tail is better. The US briefly had such a system in the postwar era.

Some may argue that because the right tail individuals are more talented, we should just keep rewarding them as they are more efficient. That ignores that these people's time is limited, and at some point you get diminishing returns. We are way past that point.

How do you favor the middle? The middle plays by the rules, so you need to enforce those rules and prevent elites from changing those rules. This means first and foremost campaign finance reform, up to and including public funding of political campaigns and a ban on political donations.

This is the hard part. The middle will never be as politically savvy and engaged as the elites. For the middle, the political system is exogenous. Thus making it as exogenous as possible for the elites is necessary.

A middle class society can defeat an elitist society because it mobilizes more people. Parliament defeated the king.

We need to stop obsessing about the modern right-left divide that has been in place since Marx first appeared. Marx got it wrong by focusing on exploitation of one class extreme by its opposite class extreme. He should have been thinking about maximum middle class mobilization if he wanted to replace capitalism.

Instead use our knowledge of the normal distribution of human ability to empower the middle where most people are. This may be a tough pill to swallow, but we need to accept that political engagement is not the middle class's strength. Therefore the more intrusive politics becomes, the more the middle gets sidelined by those who are adept at politics, whatever their alignment.

Democracy is a fabulous way to empower the middle class, since the middle class is numerous. We need more democracy, not less, and that democracy should be more expansive and not "guided" by bureaucracy. This is a huge blind spot among a certain set nowadays.

A market economy and a political system that favors the middle class over both the first and fourth quartiles could defeat our current system. Maybe you still call that capitalism... that's just a label to me.