[0] http://undeadly.org/cgi?action=article&sid=20150722182236
And note that this is about system locales which mostly concerns libc APIs. Applications are still free to support additional character sets via other means (e.g. iconv).
For some problems a locale may not be the best answer. For instance, during these conversations I learned that Japanese android phones expose filenames as Shift-JIS which cannot be listed by ls(1) when the phone's filesystem is mounted in OpenBSD. In my opinion what's needed is not a system locale that switches everything to Shift-JIS but a translation layer which presents filenames as UTF-8 to the rest of the system. Perhaps a fuse filesystem module which links to libiconv in userspace to perform the necessary translation, and presents the result at an auxiliary mount point.
...Emacs is the only package in the entire ports tree that can't use ASLR.