That doesn't contradict the notion that the Semantic Web is of growing importance in any way. RDF triples can be encoded in JSON just as well as they can be encoded in RDF/XML or Turtle or N3 or what-have-you[1][2]. And work continues on a spec to formalize the relationship between RDFa and HTML5[3], so even though XHTML2 got shit-canned, it won't hinder the ability to embed RDFa.

[1]: http://webbackplane.com/mark-birbeck/blog/2009/04/20/rdfj-se...

[2]: http://n2.talis.com/wiki/RDF_JSON_Specification

[3]: http://dev.w3.org/html5/rdfa/rdfa-module.html