This discussion of Keynes is evocative of our ‘democratic market neo-communism’ with some crucial differences: but in the end the devil is in the details. And there is a crucial threshold: the issue of expropriation. But the point here is to not let socialism become state capitalism: the creation of a ‘Commons’ requires a new legal definition of issues of property.
In any case the socialist solution will both mimic and yet distinguish itself from an archetypical liberal system. Although the model is open to all sorts of modifications, e.g. the question of worker cooperatives, etc, it deliberately attempts to take a ‘liberal’ prototype and remorph that into a (neo-)communist system starting with a definition of a Commons. Instead of a worker controlled government which is an undefined void which can end up in a one party anti-democratic system run by a vanguard, we retain the whole apparatus of a parliamentary system with parties with some variants of combined one-party and multi-party rule.
Note that in a system with a Commons, the larger public is not required to be on the receiving end of a state capitalist ‘plan’ and can demand by right a share of that common resource. There is no simple solution to a system that is socialist in the context of degrowth: a pseudo-communist elite without a legal Commons will soon legislate austerity of the larger whole as a new bourgeoisie. Our type of system must plan in advance with checks and balances a crisis outcome to balance ecological and economic issues.
But the overall result with its combined market, planned (and third sector) might well have a distant relative in Keynesianism.