"I could not find any video-enabled mobile, desktop or embedded consumer device using those open-source alternatives."
What counts as such a device?
Web developers are all moving to HTML5. One major attraction is the VIDEO keyword, which allows embedding video without the use of Adobe Flash.
But you still need a codec to show video. YouTube had a beta site that used HTML 5 instead of Flash, and it worked in IE and Chrome, but not Firefox. The issue was licensing: the YouTube site used H.265. IBM and Google had paid the license fee to use the video codec in IE and Chrome. Mozilla did not. The issue wasn't the fee, but the commitment to open source. Mozilla needed *everything* to be available in source form if desired, and the H.265 codec could not be. The license did not permit source distribution.
Google subsequently announced a commitment to make Chrome open source, and that it would end support for H.265 in Chrome. It felt open source alternatives like WebM had achieved levels of performance that made them competitive.
I expect H.265 to have a market in the embedded and mobile device spaces, but not in places like browsers where the availability of source for everything shipped with the browser is a requirement.
I think the main issue in these codec wars is only about licensing. From what I've seen in the past, the proprietary codecs (open source or not) use the same algorithms generically as the ITU blessed ones, with just enough variation, or feature purge, to allow them to sidestep the licensing issue. So I don't expect any (factual) technical superiority from the alternatives.
What makes H.265 interesting to me is that compared with MPEG-2 compression, i.e. H.262, it offers enough of an improvement as to make UHDTV feasible for the masses. As opposed to UHDTV being a cool oddity you see only at trade shows. And what makes UHDTV interesting is that at long last, here comes a TV standard that can actually match the quality of excellent camera lenses. The lens now being the next weakest link in the chain. Until now, even HDTV did not come close to exploiting what image info a good lens passed through.
The licensing arrangements will make or break H.265.