"Historically, if you go back in time 100 or 200 years, there were lots of boarding houses, social clubs, etc., in London and Paris and New York, where young people would move into the city, and that’s where they would live before they get themselves established."These projects sound great, but I think there's also huge untapped demand for dormitory-style housing at the lower end of the market. Large sources of low-wage employment - an airport, for example - often attract immigrants, domestic transplants, and otherwise people with few attachments. An option to move into a cheap room (perhaps with multiple people per room) with few amenities (shared bathroom, kitchen etc.) would likely be seized on in large numbers.
People working low-wage jobs with tight budgets often trade housing amenities in exchange for saving money and increasing convenience (like commute time). Unfortunately, many rules and regulations prevent the most natural forms of this trade from occurring, i.e. getting a cheap tiny room close to work. For the most part this simply results in more people staying poor by reducing their ability to save. For a subset more intense about saving money, convoluted and illegal housing arrangements are often the only option (cramming multiple people into single-family dwellings).
Relaxing regulations on building density, minimum parking requirements, and rules that restricts the number of unrelated occupants would be a tremendous step towards allowing these 'work dorms' to make a return.