Tim Bray want's to Drop the <!DOCTYPE>, and points to a proposal for XML 2.0.

I have to admit, I always thought XML would be at 1.0 forever, but Tim makes some interesting points:

it's usually a bad idea for a document to express an opinion as to what its own schema is. Most useful languages have more than one schema, and it?s the absolute right of someone receiving a document to decide whether it meets their definition of "valid" before they use it, so they're going to make their own decisions as to which schema (if any) is appropriate.