I cranked out something similar to this years ago called in Lua and C called moonfall, actually more powerful because it was extendable, even got on smashing magazines "best of the month" or something like that, and I'm pretty sure it didn't obsolete CSS. Actually I don't think anybody used it, not even me. Maybe because Lua didn't have the buzz that javascript has now. http://moonfall.org/
Ideas like this could, eventually, actually obsolete CSS as we know it. All it would take is for subsequent revisions of the CSS standard to include support for some of these features, and for browsers to support more complicated CSS.
With Less, SASS and similar tools becoming more popular recently, I wouldn't be surprised to see Chrome or Firefox experimentally include their own implementations.
