I should point out that XSD is different from SAX in that it was pretty clear
that no W3C or other body was going to get into the stream-oriented API
business. Thus SAX was unclaimed territory. The schema picture is different;
it is near-certain that the XML WG or some other W3C organ *is* going to,
before too long, start emitting working drafts for some sort of a schema
facility.
That said, I think the discussions you are having (in particular Paul
Prescod's manifesto of a couple of days ago) are tremendously useful.
-Tim