I think it is already in there, although well-hidden. And taking advantage
of it will require smart browsers.
A smart browser could put up the scene non-textured as soon as it was read,
and then go off in the background loading the non-inline texture files
referred to by any Texture2 nodes in the scene.
It could also tell all LevelOfDetail nodes to just use the very lowest level
of detail initially to get a rough version of the scene up, and work with
LevelOfDetail so that the objects closest to the camera had their correct
LevelOfDetail representation loaded first (while the user is looking at the
low-res versions, of course). This is all assuming that a typical use of
LevelOfDetail will be something like:
LevelOfDetail {
screenArea [ 10000, 4000, 400 ]
WWWInline { bbox ... } # Highest level of detail
WWWInline { bbox ... } # Middle level of detail
WWWInline { bbox ... } # Low level of detail
Cube { width ... } # Really low level of detail
}
In other words, provide a really low-bandwidth lowest level of detail that is
always transmitted, and provide higher levels of detail via WWWInline
references. That way, objects very far away take very little bandwidth.