f the federal government set up a replacement program though, and shipped all the JD machinery to Ukraine where hackers know how to modify the software, everyone but JD would win.

Funny you should mention Ukraine, a decade ago (iirc) Ukraine hackers cracked the JD interface and started making available a tool for farmers to manage their own tractors - John Deere sued

vice.com/…/why-american-farmers-are-hacking-their…

…medium.com/about-those-kill-switched-ukrainian-t…

Although I suspect you already knew that :-)