Document identity, yes, though document *equality* is still meaningful.  But document order is not sacrificed, it's just that elements as such don't display it.  There is still the order of values in sequences, the order of characters in strings, and the order of values (limited to strings and elements) in rich texts.

There are still sibling relationships in the three contexts I mentioned, but they are not *absolute* sibling relationships, only relative to the particular context.  In [3, 4] we can say that 4 is the right sibling of 3, but in [4, 3] it's the left sibling; however, the two 3s and the two 4s are not distinct.