To me, the cost of purchase, maintenance, and quickly out-dating autonomous machines could be completely offset by hiring qualified people to drive. 

Actually, you could hire one of the JD engineers full time and probably still be money ahead of buying and maintaining the autonomous part. Most of the basic machine maintenance will be the same as non-robot machinery. How much maintenance is really spent on the human environment of a machine? Cab filter, maintaining a/c or heater. I assume the autonomous portion of the vehicles will need some kind of environmental controls also.

As I've said many times....JD and others, you need to spend your research dollars fixing the many known problems of modern equipment you sell daily, not some futuristic design that you'll use present day profits to fund.