New UTF-16? I'm only aware of the original 1996 one, which uses all of its 20 surrogate-pair bits for the codepoint (unlike UTF-8 which can use bits to extend

New UTF-16? I'm only aware of the original 1996 one, which uses all of its 20 surrogate-pair bits for the codepoint (unlike UTF-8 which can use bits to extend to more bytes). In my understanding, "just" removing that restriction would mean completely replacing the encoding, like UCS-2 being replaced with UTF-16. The new one may have some overlap, but transitioning to it would still be a huge undertaking, and far from trivial (quite a few programs today still use UCS-2, quarter of a century after UTF-16 was introduced to replace it).