Right. Exactly.
The proprietary hardware and software are designed in-house by PS Audio and thus are optimized together.....in the same way Apple products are designed. Except for the most esoteric brands / designs, PS Audio is the only company I know of that isn't using an off-the-shelf DAC chip or is using a reconfigured DAC chip.
I guess what I'm wondering is if there's a way to take an off-the-shelf DAC chip (to keep costs lower), but still implement software upgrades in a similar fashion as PS Audio, which can evolve. To some extent, all DACs are limited to their hardware capabilities, but PS Audio has taken control of this aspect. How long they choose to support the Direct Stream via free software is completely up to them. I have no idea what they expect the lifespan of the product to be, but wouldn't it be cool to have a DAC that can last for years and be up-to-date with current tech (in terms of audible performance) for the next 5-10 years, versus being on this constant flavor-o-the-month DAC swap? Maybe the software isn't always free (depending on how big of a performance leap is). It'd be a leap from software version A to version B, maybe not version A.1 to A.2 ; The same way computer operating systems are updated. This way Bryston can continue to develop software and recoup those development costs along the way.
Of course, people will always swap gear. But, I think there are many out there who wouldn't swap so much if the gear we buy (DACs particularly) could be designed to last and be used longer even in light of new DACS coming to market. Imagine if Bryston designed something like the Direct Stream, but the user had the choice of decoding method (PCM or DSD or whatever the future might hold) at the press of a button. That'd be slick.
Not to mention, this whole idea plays into the fact that Bryston makes gear to last (per their 20 year warranty).