delirium-
This seems like a pretty hackish solution long-term.
HTML is not hackish. It can be printed and viewed on all platforms using free libraries, it can be easily indexed, and it can be converted to literally everything else using existing code. Semantic wikimarkup can be replaced with CSS classes for the appropriate tags. We are already producing well-formed xhtml pages with virtually every aspect of layout defined in CSS. This then puts us on the road to producing pure XML when browsers support it. A CSS wizard like Gabriel might even be able to hack something like alternative MathML/PNG display for formulas, rendered based on the user's CSS file.
To use our own syntax, which is indeed hackish (a mix of UseMod and our own extensions, with ugly constructs like "#REDIRECT", pseudo-HTML tags, tags with undefined scope etc.), or to define a new "abstract syntax" would be a waste of valuable developer resources. Any semantic information that may still be missing from the output should instead be included in it.
Wikitext is meant to be read by humans, not by computers. The only program which should read it is our own parser. Keeping a separate parser code in sync with ours (or, in fact, a completely new "abstract" syntax) would be a maintenance nightmare. Our syntax may look simple, but it is amazingly complex - features like transclusion, parametrized templates, image scaling, wiki table conversion, and various extensions are not to be scoffed at. And new ones are being added all the time. That is good! The fact that we support stuff like hieroglyphs makes Wikipedia much more interesting for academics.
Now, rewriting the parser in another language to create a fast cross- platform library might make sense, but for completely different reasons. The only reason I can see to include the wikitext on a CD-ROM would be for offline editing, but for that you need a fresh copy of the source to avoid edit conflicts, so you need to fetch it from the site anyway.
Erik