That's a really good observation. Better to keep our ag going by any hook or crook necessary, than to let it die out and -- because once it's gone, it's gone forever. It's not possible to recover cropland from suburbia, nor is it likely that public grazing land sequestered out of ranchers' reach will ever be returned to the pool of usable acreage. (And those who think we should farm rather than ranch any such land have obviously never seen the American West.)
Somewhat in the same vein, I've speculated that a great deal of the anti-farmer water policies currently at issue in California are in fact not about water or fish or anything local at all, but rather are very likely being lobbied by food *importers*.
This has already been done once -- Prop2 (which outlawed modern egg production in CA) was fronted by HSUS, but the money came from egg producers in India, China, and the Phillipines. (I found some documentation on that, back when it was happening.)
Kill our ag industry and what will we eat? Imports, obviously. We're one of the few countries both large enough to be a markiet and rich enough to buy our food, at least for a while. But over time it's a great way to become a client state. :(