His essay "Marxism and Humanism" is a strong statement of anti-humanism in Marxist theory, condemning ideas like "human potential" and "species-being", which are often put forth by Marxists, as outgrowths of a bourgeois ideology of "humanity".
And, also from wikipedia
For Althusser, the humanism of Marx's early writings—influenced by Hegel and Feuerbach—is fundamentally incongruous with the "scientific", structure-concerned theory found in Marx's mature works such as Das Kapital.
Does this later, scientific, Marxism really make sense, given the relative obscurity of Marxist ideas?
Seems to me that it's only in a blend of the so called "humanist" and "scientific" Marx, that we can say that Marx's communism may be realisable, as that would rely on different forms of argument, and observation -- is the working class still a potential catalyst for revolutionary change in humanistic terms.