The Web Publications work over at the W3C remains utterly depressing to me. Mainly because I remain convinced that the IDPF/W3C merger guarantees that it will devolve into a reimplementation of ePub, which isn't really what browser vendors want (who want nicer ways for making the regular web publication-friendly).
So browser vendors will ignore it.
And Amazon will ignore it.
And it'll just be a rehash of the current, limited ePub ecosystem nobody likes.