Rather than shortening the workweek so my a better idea to move the retirement age forward. You go to school as normal, then work full time for ten years, save enough money that you can live off the interest/afford your own robot whatever to make you passive income, and retire around 30.
That is a more difficult way to do things because it either presumes that people are going to magically get really good at long-term planning/saving, or it presumes that we will enact a social insurance system that will cost a lot more while people are working so they will not starve once they are not. Neither seem plausible based on history.
I think that people need productive things to do in some way, shape, or form. I see my retired father who genuinely seems bored, especially in the winter when he can't golf. He's not the type who would volunteer at a day care or try and invent something in his spare time. Don't get me wrong - he's glad to be retired after nearly 50 years of working a physically demanding job, but I think he would have gone crazy if he had stopped when he was 50 years old.
Shortening the time we are mandated/expected to work would work better. This used to be the case in the form of longer vacations based on your years of service. The economy doesn't work like that anymore, people don't put in 30 years at the same company and accrue 6 weeks of vacation. They move around and start their seniority-based vacation from scratch every 5-10 years - and few companies give out 6+ weeks anymore anyway, it's more like 2-3.
I would love to see a work culture where hours could be more flexible. For example, I'd love to be able to say "this year, I would like to take 10 weeks off because I have young children, but in a few years I won't have as many demands so maybe I'll only take off 3". There is no formal mechanism for that, and if you informally ask it of your employer, your professional reputation will be tarnished. I asked to go part-time when my first child was born - I wanted to take off every other Friday, basically a "90%" schedule. I was told "no" in no uncertain terms. Not possible. And I work for a decent-sized company.
There are three major stumbling blocks that keep people tied to their jobs: healthcare, retirement and college education for their kids. If I knew that my retirement was secure and that my kids would not have to pay for college, I might consider working less or pursuing something different (but less lucrative or maybe more risky). Those are really big important expenses to have to worry about though.