Changes that might be controversial
I would suggest that ISO-10646 become a "reserved name".
MIME-VERSION: Changed to 1.0, but retained. Changed syntax to
RFC 822 "text".
Have you included the notion that version numbers shall not be used
to imply changed syntax or semantics for old used header tags?
I think it is critical, and this is borne of experience with "object
registration systems work" that we not ever redefine the syntax of
semantics of RFC-established header fields. The problem with any
redefinition of any object with an established name is that all
implementations ever after must deal with potential ambiguities,
including all prior implementations which are now subject to breakage.
To a large extent, this is the same argument we (many of us) applied
to the amazing idea of "just declare 7-bit SMTP systems broken". It
was a bad idea then to redefine the "SMTP Object" and it is a bad idea
any time in the future to redefine any object without overtly giving
it a new name (or identifier), just because it should never be
confused with an old object of the same name (or OID).
Cheers...\Stef