What about conformance issues? Is a MIME-compliant mailer still going
to have to work with richtext, but not with the presumably-more-complex
(harder to parse) Mail-SGML?
I think this is a separate issue from separating the documents, but I
would hope that things evolve toward "Richtext conformant" and "MIME
conformant" separately, with the former presumably requiring the latter
and the latter suggesting the former. If Richtext is good enough that
lots of people are going to implement and use it, then it shouldn't need
the main MIME message-format standard to drag it along; if it isn't that
good, MIME shouldn't carry it as extra baggage.
Just one opinion.
john