I don't think it's a realistic picture at all.
Unless there are unbelievable U-turns regarding public land, growth in population density can only occur on freehold land - loss of significant tracts of farming land is possible but there are controls. We'll just get megacities IMO, that's the world-wide trend. The blaze of lights shown covers vast areas of National Parks and State Forests etc, ain't gonna happen.
The map's just some person idly filling gaps between existing population areas with white, without understanding why those gaps are there.
Cheers -