Are there likely to be real-world cases where this happens - and the effect is detrimental enough to actually matter to anyone?
Surely we're debating "when is it good enough for anyone sane and reasonable?" not "when could a hypothetical oracle be fooled 100%"?
And as I said, really, the main reason to avoid lossy compression at this point is due to generational loss and post processing. Lossy compression should be considered a final processing step - what you do to store music that is then going to be delivered directly to a listener, unaltered. If you're going to do anything else, you'd do much better with a lossless version.
That is not to say, of course, that if all you have is a lossy version, it is a major problem :-)
For the record, my lossy format of choice for e.g. putting stuff on my phone is 96kbps Opus. Even that much is excellent for casual listening. But I much prefer to keep lossless FLACs as my primary archival storage - not just because that way I can take advantage of better compression formats as they come (e.g. how I moved from ~130k Vorbis to ~96k Opus), but also because compression makes a massive difference with certain kinds of processing and editing which I sometimes enjoy doing. All the psychoacoustics go out the window if you start doing things like subtracting instrumental mixes from full mixes to get vocal tracks out.
With most samples, yes. The issue, as I said, is that psychoacoustic codecs are basically heuristic by definition, and so you can pretty much always find counterexamples. It's possible to say 320kbps MP3 is indistinguishable from uncompressed for most samples; it is not possible to say it is indistinguishable for all samples, present and future.
It's also the case that lossy encoding is a bad idea if you're going to be further processing the audio in any way; repeated transcodes definitely start bringing out the artifacts more. So lossless music is always something worth having as an option.
Now, when you start talking about "high-resolution" 96/192k 24b stuff... yeah, that's just as good as healing crystals.