We have empirical evidence of what happens when agriculture subsidies disappear - New Zealand ended them all in the early 80s, when they were having financial trouble. Within a few years, their farming sector was actually healthier, because they moved away from being subsidy whores and became farmers, and it turns out that farming is a better business. Also, a revolution? Less than 1% of the first world is farmers. Who exactly would be doing all this revolting?

As for the machines replacing humans bit, I specifically mean "machines" to be the unintelligent ones - AIs are people, not machines.