The difference between jailing people and massacring people is HUGE though. I do think it's very difficult to get around the problem of people not wanting to g

The difference between jailing people and massacring people is HUGE though. I do think it's very difficult to get around the problem of people not wanting to give up private property when a society shifts into Communism. But in the future when/if automation can provide a very high standard of living with far less labor inputs, maybe it will become something viable in some form without massive heavy-handed coercion. I think varying forms of somewhat Socialist democracies will probably win out in the next century or so, but it's very hard to predict given that some potential advances in technology could dramatically reshape economies and governments.