I have a 39 9N. A new 4wd John Deere track tractor can run 600K. It can do a field by itself. The farmers have phone apps so they can setup their combine just how they want them for each crop or condition.
The dairy farmer that rents our crop land has gotten to the point of hiring out planting and harvesting. He still does all of the manure hauling and the hay bailing but when you can get it done in a matter of HOURS versus DAYS, it makes better sense to 'rent' some guy or gal with a $600K 'mortgage' hanging over their head, than to have that debt yourself. Especially in a volatile dairy operation.