Large SVG files

Has there been any discussion on how to handle partial downloads of very large
SVG files (>1GB)?  In this case, the viewport would only be a small percentage
of the entire image.  The browser would download only the graphic shapes that
are visible, and could automatically keep a cache of previously downloaded
shapes as the user pans around.

This functionality could potentially be implemented by including some kind of
spatial index attribute on each shape, or by providing a way to divide the file
into smaller sections.

This functionality would be very useful for mapping applications.