it has nothing to do with such subjective thing as "morality". The idea is that at some point the society produces so much that the distribution mechanism known as "market" is just useless overhead, taking more resources for the sake of "market" than the amount of production it makes possible. So "the market" gets discarded. The "morality" does not matter, because a) there is so much of everything, even the greediest people will be sated and b) people are basically good, so if the work is not hard (and there is no hard work left, see (a)) they will do it for fun. Yes, point (b) comes close to "morality", but Marx backs it up with other things - I am not good enough Marxist to remember them.

I don't think a single country in the known universe reached the conditions need for real Marxist revolution. Nor do I hold my breath.