Indoor square footage is not, and will never will be a relevant constraint on food production.
At $400/square foot to build a mall, and $XY/square foot/year to maintain it, the only thing that makes financial sense to grow in one is black market marijuana.
At $400/square foot to build a mall, and $XY/square foot/year to maintain it, the only thing that makes financial sense to grow in one is black market marijuana.