well, it depends on what youre happy with. technically im sure somebody said the same thing when good HQ pre/AD combos like the V3 came out. As easily as digital technology can become dated, 20 years later you can still go make world-class recordings with a V3, in a studio, yet alone a relatively noisy live show environment.
Heck a sax>SBM setup from the 90s was putting down phenomenal dynamic range for our purposes esp with the noise-shaping of the SBM
that said, perhaps you could have highlighted this part as well:
Since no combination of ADC, mic and preamp can achieve 25 bits of instantaneous dynamic rangeit seems that the ADC portion is ahead of the rest of the signal chain, for now (forever?). However, unlike previous improvements in digital technology, the 32-bit float architecture only improves the sound when compared with a
less-than-ideal setup of lesser bitrate. In other words there is no sonic advantage to a 32-bit file vs a 24-bit file
at proper levels. Which depending on setup (background noise, mic noise, amount of gain used, etc) could mean anything where your peaks dont hit -12dBu to where your peaks dont hit -48dBu. Again, its a container for your data, if you are carefully putting your data in the container there will be no difference. if you are missing the container with your data its a huge problem. and an easy fix in this case, with the auto-ranging ADCs which "move the container for you" as needed.
will you want to upgrade someday? sure... when a recorder that sounds as good as your mixpre is the size of your phone. that will be another 20+ years though, and will likely only offer diminishing returns, if any, over your current setup in terms of overall sonic quality for our purposes
next stop is microphone signal path, it seems that paused for a bit with the digital technology, but i would imagine thats what we see next. Every manufacturer has their own way of powering their mics, from the permanently polarized DPAs that take a trivial amount of voltage/current, to the schoeps who have cut the power requirements of their preamps by nearly an order of magnitude in a few decades
couple these advances with digital microphone preamp technology (advantage being less power required to generate a hot signal to compete with noise), as well as the ever evolving ADC and op-amps, and, basically its only going to get better as far as tech.
so i guess to circle back, you asked "there might not be a need to ever upgrade a recorder after this."
was there a need before this?