<html>
<body>
<svg::svg width="100" height="100">
<circle .../>
</svg>
</body>
</html>
The double colon "::" would be different to the single colon in that it would be
sticky - descendants would be put into the same namespace without the need to
prefix them too.
The W3C would maintain a registry of *default* namespace prefix bindings, kind
of like how there's a registry of content-types now.
No need to specify an (the "xmlns") attribute - it's much easier to write a
prefix, and much much easier to remember a simple prefix than a dated URI.
No need to prefix the closing </svg> tag (what's the point?).
Any existing XML content that binds a prefix to a namespace other than W3C's
default would continue to work in new parsers, since their binding declarations
would override the W3C's defaults.
Jonathan