Perhaps - I would think in many cases, an equilibrium would be reached. Comparatively few people in any industry are wholly irreplaceable. Still, should something like this just pop into law tomorrow, one could expect a large group of experienced specialists at the top of a wide array of fields to decide to retire, to disasterous effect. Given time to settle in though, I'd wager it likely that talent would filter up to replace any losses at an equivalent rate.

Ultimately, people as a whole like to work. They dislike working under poor conditions or doing jobs that don't feel rewarding. A law like this would generate a lot of change, but I just don't see that change being disasterous given sufficient adjustment time.

Our goal as a society should be to maximize happiness, not maximize the number of people who are working.