I don't think idiotic zoning rules are libertarian. To me the libertarian stance would be to have as few regulations as possible and see if these "401k millionaires" can compete with deep pocketed developers who could spring up multiunits, make more money off that land than a single McMansion could bring, and increase the tax base, bring in more businesses now that they have a growing market, and raising property values over time. (Okay, caring about increasing the tax base isn't very libertarian.) But I guess popular libertarianism has strayed pretty far from original principles anyway.

Btw these potential farms would be better served by not being overtaken by and competing with suburban sprawl and development. Density at an inner core would hopefully help rural areas stay truly rural. It actually cruelly takes up potential farm land to force non farmers to develop in this way.