>>715426064
At the level of Kowloon, probably not, but you can get pretty dense, comfortable living.
The problem is that this sort of thing requires a level of social support, and motivation to do good, instead of making money that's currently unrealistic. Put everything along a central rail artery, with capillary trolley and road routes. Any roadways that exist are 90% for transportation of goods or disposal, not private use.
You'd also have to convince huge quantities of people to agree to give up their property and move into the box. Some would, but you need to get all of them.
This sort of living basically requires the lofty ideals that the Soviet union tried to do for a bit, before everything broke. Commie blocks on advanced, mass public transit, where people goods and services can be efficiently transported, and all the wasted space of inefficient transport can be lived in.
Even better, you can put this in undesirable, infertile land, to get housing out of good agricultural, mining, or other functionally useful land, and you have vetter resource efficiency, too.
