for Marx, revolutionary socialism is inevitable, and, if anything, should have happened by now. In all fairness to Marx, socialist revolutions have taken place in all corners of the world, from the Bolshevik revolution in 1917 to the independence of countries like Cuba, Vietnam, and other Third World countries during the Cold War.
But even then, it is hard to say that these revolutions have achieved the goals stated in the Communist Manifesto: inequality still persists, the State is still very much alive — arguably even more oppressive — and most of the communist countries of the Cold War era have reverted to liberal democracy.