HTML5 is here courtesy of our friends from WHATWG. HTML 4.01 will have an officially sanctioned successor after all. For me, this indicates that XHTML 2.0 has no raison d’être now but who knows?
HTML5 has a bright future. And so has CSS and Javascript. I would advise all aspiring Computer Scientists to get familiar with the latter. Javascript is an extremely powerful programming language and will power the client-side portion of many of the applications we will use in the future.