Certain protocols will be limited by format. XML is useless here. WML and WAP are necessary for you wireless freeks to play games and communicate. Bottom line HTML simply doesn't have the ability to expand further to accomodate needs of current technology. V4 will be replaced by V6 to create trillions of more opportunities for addresses, we're running out now. DHTML is capable of neat animations and great ability to position, and the ability to base things on user reactions - it's cool.
It will be less tolerant also. In this format there is no need for tags, others will compensate for non-closure in some cases, but in the protocols I described mistakes "aren't allowed". Paragraphs require a closing tag...
What do you do with DHTML?