I hope content publishers will find publishing HTML5 video convenient enough to drop Flash. Once publishers are all on board the HTML5 video train, they have the opportunity to experiment with new (and unencumbered) codecs without affecting their user experience.

Lots of video will be played on mobile devices, so any codecs without hardware support is very likely to affect user experience in a noticeable way.

Is is very difficult to find any HW without VP8 support. Android mandates it since 2.3, so since then the SoCs used in mobile devices support it.

Only Apple does not support it for political reasons. Just like they never supported Vorbis.