You bring up a good point, but I don't think the status quo will be able to persist. This is because of the pace of at which efficiency increases. To be honest, I haven't looked relevant data, but I imagine our rate of improvement is non-linear. As technology advances, it increases the rate at which technology advances. Thus far, demand has scaled in conjunction with the increases in supply. I don't believe it will be able to keep up in the long run though. You just won't need as many workers.

You'll also notice that the average worker now has far more education and training than in the past. This is a side effect of our increased dependency on technology. As more and more specialization is required, the barrier to entry in the workforce will just become too high.