The Demise of Shopping Malls. The Rise of High-Yield Agriculture?

In a few weeks, Jeff Bezos and the team at Amazon will sit down the CEO's of the top global consumer product brands and make a very bold case to them: "Cut out the middle men.  Stop worrying how your product looks on the shelf.  Don't even worry about the end retailer.  Make stuff, and we'll take it from there."  A gross over-simplification?  Yes.  However, Amazon believes they are a few years away from being able to reach 85% of the American population within an hour.  The reverberations of this have been shaking big-box and mall real estate for many years.  There is even a video series touring zombie shopping malls. 

People a lot smarter than me have been scratching their heads on what happens to these spaces, and Atlanta's own, Clark Howard, threw out an interesting suggestion: High-Yield Agriculture.

Off the top, it sounds nuts.  However, having talked to a few friends with investments in commercial agriculture, they laid out the basics for me...

A really productive farm is good for about $10k/ac in production revenue.  High-yield indoor farming, as is being perfected in northern Europe and Japan, can yield $60k-$70k/ac by accelerating the growth cycle and removing all weather variables.  You have to make up a lot of the extra costs associated with by practicing as close as possible to your end consumer with a skeletal labor crew.  The margins in the US are too thin, unless you're growing weed.

In a vacant shopping mall, you have high ceilings and utilities in place.  Now for the hard math, how cheap do you have to get the land to make this work?  

More on this to come, but consider the seed planted...

What'd I miss here?