Inline flow of alt text.

Hi list.
Looking through http://www.w3.org/html/wg/html5/#alt I can't tell if  
the points made in http://www.hixie.ch/advocacy/alttext are normative  
in HTML5 or not. Specifically the requirement that an image's alt text  
flow inline and not be constrained to the image's frame.

I would like to see that they are, assuming no valid counter-arguments  
can be made.

— Nicholas