Worth special discussion. The point is that current Xpath is not really simple for understanding or explanation and it could be improved with 'making it more OO'. And it could be easeir to write and to maintain. Nothing could be used as-is. Current schema efforts are first of all providing a strong support for ordered items.
Unordered content is a special case of messy content.
Another case of messy content is mixed content and it is not given enough attantion. XML is mix of structured and unstructured content. Schema consists of rules and constrains. This 'pure OO' comes from the universe, which is driven by structured content, so not everything from that universe could be used. XML is really special, so should be a solution.