[whatwg] An alternative to <picture> and srcset, is this realistic?

Hi all,

have any of you seen this proposal for an alternative solution to the problem?

http://www.w3.org/community/respimg/2012/05/13/an-alternative-proposition-to-and-srcset-with-wider-scope/

I like the general idea and from an author perspective this seems
great; but I know nothing of the browser/vendor side of the equation -
is this do-able?

Cheers,
Matt