... but it would require a complete and total shift in multiple entire societies around the world, all parts of them changing all at once. Utterly impossible in reality.

I think that there are still people who would strive to excel in their field even if there wasn't a need for more money. Lots of people wouldn't, but those probably aren't the people who are doing the excelling and the inventing right now anyway.

But the whole system would need to shift all at once. For most jobs, 21 hours of earnings would, as you said, not be enough to pay for the basics. The entire system of profit would need to be revised in order to lower prices. At the same time, lots and lots of people would have to be willing to live with less all at once. They could do it, sure, but why would they want to? More free time would be nice, but if you want to travel or invest in hobbies, you still need money above and beyond basic needs.

That's not even taking into account the fact that if consumerism goes down by a large percentage, and if people have less money to spend on random things, then all of a sudden there are a lot fewer manufacturing jobs and service industry jobs to go around as well, and you might be right back to the same place as far as unemployment goes.

An interesting idea, but very unrealistic.