whatever

Basically for all areas with any development to be walkable then all areas either have to be 100% non-developed or 100% developed, with no in between.

Are you saying that the only areas that are walkable are wilderness and buildings?

Because that's not true.

It's just not realistic for these lower density areas to be walkable, or just randomly cease to exist.

You can increase the walkability of suburbia by ensuring safe pedestrian infrastructure and providing shade and lighting. And by putting walking paths and small parks between streets to make the area more permeable and pleasant to pedestrians.

It can be done without dramatically increasing or eliminating population density.

Or are they going actually bulldoze entire counties worth of developed land to turn it into farm land?

Farmland isn't particularly walkable.