The nature of the dialectic is for it to continually and fluidly evolve, every now and then contradictions mount to a point of qualitative change and give rise to a new system that resolves the contradictions of the last, but gains new ones. It never ends. Marx only said, capitalism will bring about socialism, which will in turn bring about communism. Everything after that is too far away to really make any concrete statement that isn't grossly biased by the conditions of our time.