Yes, anti-capitalist theory does need to move beyond Marxism, but it doesn't need to move to (as Joseph Heath seems to believe) Rawlsian liberal-egalitarianism.

Perhaps this is the Mutualist in me chafing at Rawlsianism in general, but his emphasis on "Liberal vs Decent (vs Other) Peoples", and his envisaged world order that can both "tolerate" other societies who disregard certain human rights, but also choose to intervene (as a structural component of the philosophy) into societies which they deem not "tolerable", just feels like reinventing the "Rules-Based Liberal Order" of Western Liberal Militarism with a moral (self-)justification, rather than a monetary one. Same tune, new instrument. His focus on Hierarchy is anathema to his supposed desire to produce equity or equality; equality is the absence of hierarchy, which obviously can't be enforced at a micro-level, but he's gone the dead opposite direction, and somehow come to the conclusion that equality can be forcibly imposed (by someone with an unequal amount of power, of course).

Heath linked to a piece by Freddie deBoer on the inability of Western (Neo)Liberalism to create the outcomes it desires, and frankly I find that piece far more persuasive than Rawls' insistence that you can maintain a massive, national and international-level hierarchy but actually everyone will do what's "Right". Any sufficiently large or permanent hierarchy will first and foremost seek to sustain itself, no matter who or what is in charge of it, and there's no inherent way to prevent a system from doing or becoming bad. Systems and structures and even societies themselves are merely organizational tools, and no tool can prevent itself from being misused.

It makes me even more nervous when that large-scale, International "Order" is turned into a moral imperative, as it is in Rawlsianism. Now you're just reinventing the Holy Roman Empire, with some council of supposed representative citizens in lieu of a Pope, but still operating under the auspices of being the ultimate arbiter of morality.

The solution to inequality isn't creating some unassailably-powerful liberal-egalitarian super-entity, to enforce worldwide human rights, it's to dismantle structures of control that perpetuate systemic inequality.