What's missing?

XML routing While we have 'XML portals', there hasn't been a lot of consideration given to routing different types of XML documents through multiple systems. XML protocols which call themselves 'extensible' are capable of handling this, but developers need to manage the process.
Distributed thinking Many folks think that meaning is something that should be developed by committee, standardized, and set loose on an eager community. Community-based development, however, may not mean that communities gather in a forum to develop standards - it may just mean that they get along well enough with their own ad hoc work, which periodically evolves into something worth standardizing.
Enough application openness The standardization model - a single vocabulary, a single process - and the dream of off-the-shelf software threaten to strangle the possibility of really taking advantage of 'Extensible' in any vaguely profound way. By encouraging the use of a standard set of vocabularies without inviting extension, such projects promise to keep most people (who keep their jobs) from participating in data description even at levels which are common today.
Letting humans be humans Making business easier for machines shouldn't come at the cost of thousands of years of human business experience. Halting the evolutionary process just because UML and XML Schemas seem like good concrete doesn't seem like a recipe for success.