Most far leftists would like us all to live in concrete towers, in small apartments, sharing a common bathroom area for maximum efficiency and density. Probably with mixed in sources of food and drink but not much in the way of consumerist "excess". It doesn't account for ideas of freedom or individuality or needing to see the sunlight. The problem with this is that it doesn't account for the rebellion that happens when you cause people to finally break from this unnatural condition and a million years of evolution.