I don't know about the Socialist Party, but the material I've seen from the Greens doesn't challenge the basic assumptions of capitalism, liberalism and social democracy, so in effect the people they are going to relate to among Blacks and women (as political categories) are precisely the Talented Tenth, because that's what social democracy is all about -- the bourgeoisie with a human face, you might say, achieved by replicating bourgeois relations and ideology among the lower orders and thus incorporating them into the system.
The people around today who do challenge liberalism, etc., are mostly anarchists, so they're not likely to be big on electoral organization and conventional politicking. The old CP must have had some idea of how they could turn electoral victories and government power into fundamental social change. The idea is too sophisticated or too naive for me; I don't see it. But it could have given them the moxie we don't see today. Suppose they were naive: recall what Nietzsche said about the necessity of ignorance.