Above I mentioned two ways that XML might get displaced. One on the supply side (data normal form) and one on the demand side (presentation). There is a third - data exchange. Exchange is where the powerful network effects are - always! RDF is better for data exchange than XML. It's easier, it's simpler, and it is far better for layering, mixing, and creating new standards.
This trio, and the standards around them, are key to making anything happen in the net.
- Supply: writers, data, storage, normal forms, etc.
- Demand: readers, presentations, ui, etc.
- Exchange: messaging, subscriptions, polling, push, etc.
The RDF folks think that the demand side is where the leverage is. That’s wrong. Content is not king! Exchange is king. In the world of ends, the middle rules.