Alex Tabarrok has as solution to the problem of capital accumulation that Thomas Piketty identifies as the driver of inequality (Capital in the Twenty-First Century): Change the birthrate of the rich:

Increasing fertility rates would do the trick: “If every wealthy family has 4 children, wealth per person doesn’t increase and so inequality does not increase. . . . If the wealthy consume about 20% of their capital income (still a very high savings rate) and have just 3 children then again we have approximate balance and no increase in inequality over the generations. . . . Piketty’s ‘patrimonial capital’ contains its own internal contradiction. The more patrimony the less capital.”

So would reducing fertility below a certain rate: “If the rich as a class have fewer than 2 children then it follows inexorably that their time is numbered, albeit without first creating a small number of very rich people.”