What will all the serfs and slaves do for a living, now that we have tractors and combine harvesters? I mean, that's > 90% of all jobs! How will we cope with 9

What will all the serfs and slaves do for a living, now that we have tractors and combine harvesters? I mean, that's > 90% of all jobs! How will we cope with 90% unemployment? (it should be obvious that this is not serious... humanity has survived "machines are taking all the jobs" many times before, and it will survive this one too)