4 day work weeks will be required to compete as structural demographics compresses the working age population [1] [2]. For example, over 1000 school districts in the US have moved to a 4 day week to retain teachers, as they have no other choice [3]. There is evidence it works in many industries (office work, manufacturing, law enforcement, government) [4]; it might not work everywhere, but it can work where it works.
There is no reason not to ratchet down the work week as productivity has increased, and most people work to live, not live to work (as indicated by the satisfaction indicators in these 4 day week trials).
More diversity in this area could bring a worldwide increase of productivity, wellbeing and result in an economic boost.