XHTML and CSS are here to stay for a good while.. for one thing, becuase of a point already noted that browser can parse XML/XSL differently... and just like Javascript (I know thats a very different comparison but bear with me here) you're gonna get attack of the browser wars with a certian Redmond giant addeding in "special" features that are incompatible with others.. it's happened also with CSS and colored scroll bars.. well the list can go on...

But I do think that perhaps eventually XML/XSL could take over,, but by then we'll prolly have some new-fangled markup language / script / interface hybrid or w/e to take over that..

It's a vicious cycle.. but an in interesting one at that