To me, there is only one way to achieve economic stability and sustainability without creating one kind of ponzy scheme or another: A vertical Spectrum that has Capitalism at one end, and Communism at that other.

At the top, for the entire globe, there is capitalism. Natural Selection applied to property. Economic Feudalism. There is no way for there to be anything else, as there is no way to force the entire population to abide by a single economic structure. (The very act of forcing someone to live a certain way creates a class system that has people living by different rules.)

On the bottom there is the standard household family, which lives almost as a commune. This is really the only way that a family unit can survive, raise children, and prosper.

From the commune of a family household and moving up towards the entire global economy is a gradual shift that becomes less and less socialist.

Household family, extended family, small businesses, cities, counties, medium businesses, states, large businesses, nations, super businesses, and banks.

Each nation, each culture, of course, would need to have the freedom to interpret this scale on their own.