We don't need to do anything of the sort. If that was a real problem then prices for agricultural land would be higher.
Back during WWII, suburbanites turned their lawns into "victory gardens" and grew vegetables. It's easy enough to do the same thing again if it ever becomes necessary.
production yield of a victory garden is still vastly smaller than a scaled-up effort. You can't avoid the economies of scale. Europe has long used stacked housing (people live in 'flats', etc) in place of a discrete hunk of land with their own castle to sit upon.
10 people can work together and use 10 plots of land more efficiently than 10 individuals using 1 plot of land each. We just don't have a land shortage to the point of making availability an issue.
