I think any debate about the potential of BluRay for high quality audio has to look at the total package and not just the bigger numbers attached to the raw datastreams.
Take any CD, stick it in a CD player OR DVD player OR DVD-Audio player or SACD player OR BluRay player OR most games consoles OR most computers and press Play and *it*just*plays*.
Take a digital feed from the outputs of pretty much any of the above, and feed it to an external DAC, and the sound improves.
Neither of these things necessarily apply to a BluRay audio disc — they certainly didn't to DVD-Audio and there's no evidence that record company executives have become any more interested in ease of use or sound quality since that debacle.
On the basis of the small number of so-called "audio-only" BluRays I've tried over the last few years, the very best you can hope for is that the disc will halt on insertion till you turn the TV on and work through the (completely arbitrary) menus to select the sound format you want, while being assailed by corporate logos and background sound excerpts you don't wanna see or hear.
In most cases they simply start to play with *some* default format, probably not the one you want, and there's no way to set the player to default to a particular signal type the way an SACD player can be set to default to a layer. You have to stop playback, select the menus, select the signal, restart playback at the beginning (simply pressing play will typically restart where you stopped).
Similarly, attaching an external DAC is often futile because the digital outs are forceably downsampled to 24/48 at best for copyright reasons.
It's true that when you finally get to the playback, having switched off the TV you didn't want to switch on the first place, the sound quality of such discs, whether because of the higher resolution or superior mastering, does appear to be better than the same material on CD. But the hassle of getting to it...
In short, the combination of forced video navigation and forced use of limited quality internal DACs are likely to ruin the BD-audio experience (as it did the DVD-Audio one), and the utility of HFPA, or any other hires launch, depends on eliminating both from the outset.
I have no confidence at all that the suits responsible understand either issue.