Not "usable-as-in-present", but "usable-as-in-available".

Having less cars drives up the value of land, making land more expensive for everyone, and making that land less usable for any one person specifically.

You just repeated what he said... while also repeating it again. I want to know how having less cars drives up the value of land.

A huge chunk of American housing supply is in places that only made sense to settle because they were connected by freeways to downtown parking. Take that away and there will be just as much money, chasing less land.

Err, no. It's because the government heavily subsidized it at the detriment to city centers. You don't have to be NYC. City centers by their very nature our extremely economical beneficial and affordable.

Our current housing infrastructure is in no way reasonably affordable or even sane. Building houses in a dense manner is not expensive.

I'm not sure what the confusion is here.