Laws of supply and demand at work here.
Even if one day Ti pulls the plug on pcm1704. There is still plenty of other r2r dacs in the marketplace that will sprout out to fill the demand gap. Example:
https://hifiduino.wordpress.com/2014/10/12/r2r-for-the-rest-of-us/
the thing is there is money to be made here, maybe it's not worthwhile for mega corps like ti but for small scale firms, maybe it can be profitable to produce r2r dac.
Or maybe one day ess or akm(or in my wildest dream, chord) comes out with a sigma delta dac that exceeds anything r2r can output.
Very interesting - and looks to be very well thought out.
Your final sentence suggests that we may be on the same page here after all...... assuming that we can actually determine what performance differences account for the differences people seem to be hearing, there's no reason to assume that we won't be able to "tweak" current D-S DACs to match them...... or that some new type of DAC altogether may not turn out to deliver the best of both.
This is why I would very much like to see this discussion evolve from "R2R DACs sound great, D-S DACs do not, so you should buy an R2R DAC" to something more like "all of the DACs I currently like seem to be R2R DACs, so let's find out what's really different about them as compared to all the D-S DACs I don't like, and figure out how to combine the benefits of both". Perhaps there really is something that R2R DACs do well and D-S DACs simply cannot, or perhaps there's just something that D-S DACs currently do badly because the very smart engineers who designed them didn't consider them to be part of their design, or maybe, just like tubes, they simply sound "a bit different" and some people happen to like that difference.
From an engineering perspective, D-S DACs perform very well in most ways, and the ways in which they are less than perfect are such that we wouldn't expect them to be audible. (For example, some D-S DAC designs are known to deliver a noise floor that is not perfectly smooth under some conditions, and this is a flaw. However, this does occur, we're talking about modulation in a noise floor that's down 130 dB, so it shouldn't be audible.) Either we're not measuring something that in fact turns out to be important, or some of the assumptions we've been making about the performance measurements we have aren't right, or there's something else entirely going on (perhaps the R2R DACs that people like actually share some sort of euphonic coloration).
ESS has a history of designing DACs specifically for use in high-end audio products, and of being willing to consider both specifications and "listening tests" when "fine tuning" their DACs, which suggests to me that it would probably be more likely that they would be willing to expend a bit more effort to develop a specific "audiophile friendly" new DAC chip than for someone like TI to do so.... but I could well be wrong there.