In the case of languages, it's political. China wants people to think of themselves as Chinese, not as Hakka or Taiwanese or whatever. Part of that is getting

In the case of languages, it's political. China wants people to think of themselves as Chinese, not as Hakka or Taiwanese or whatever. Part of that is getting people to speak Mandarin as their first language. Hakka could probably be documented and preserved pretty well for academics to study in the future. If people were only interested in technical questions like how languages developed over time or what languages had what features, that would work pretty well. But it's the politics that people are interested in here. BTW, it's not immediately clear that having a lot of little groups with a strong identity separate from the national identity is good. If you look at places like Afghanistan or Iraq (or really most of the middle east), people only identify with "their" kind of people. When it comes to an election, they just vote for the candidate that has their race or particular brand of religion. Language, race, and religion tend to divide people as well as unite them. But I don't really know much about the Hakka or how they fit into China, so it's hard to have a reasonable opinion on how good or bad an idea "keeping Hakka alive" is.