Uh, what it says. The author has a theory about why XHTML2 didn't succeed, and he's explaining what it is. The W3C recently shut down the XHTML2 working group,

Uh, what it says. The author has a theory about why XHTML2 didn't succeed, and he's explaining what it is. The W3C recently shut down the XHTML2 working group, hence the pun in the title.