SRFI 163 is still in final status.  Its sample implementation is part of Kawa Scheme.

After some public discussion, if there's general agreement, I recommend that someone put together a unifying SRFI explaining the changes in detail, with updates to the sample implementations and tests.  This might be a group effort, i.e. there might need to be several co-authors.  Assuming that the new SRFI is finalized, I'll add a PFN to every affected SRFI, referring readers to the new one, and I'll add See-also links everywhere.