The trick would be getting people to have and grow their own edible lawns. Then the cost is the same as keeping the lawns of today, but there's a more useful return. It's only a values issue. In Russia for example small gardeners produce 40% of the nations food. http://naturalhomes.org/naturalliving/russian-dacha.htm

And perhaps the evolution of tools like https://farmbot.io/ An intelligent 'lawmmower' makes your permaculture for you.