[gregorio]

 
Does that not depend on the music?  For most all recorded music, the noise floor of the recording should be higher than the digital noise floor, since getting much above 60 dB on microphones, even in a recording studio, is difficult or impossible.  But if a hypothetical instrument were voiced say with peaks -40 dBFS and that was the only thing going on at the time, would not the digital noise floor be higher than the noise of the recording at that point?  Or rather, the noise contributed by the recording of the instrument does not add to the noise level of the 16-bit master because of the 16-bit digital noise floor (with certain other conditions met and further handwaving).  This is a fairly artificial example though, but that was what I was referring to about a potential extremely rare fringe case where it is possible to tell the difference between 24-bit and 16-bit.  Maybe the wording was wrong earlier.
 
Anyway, for any kind of sane recordings and not strange examples concocted in the lab, 16-bit is fine, as in indistinguishable from 24-bit or higher.
 
Your point about the 16-bit digital noise floor being irrelevant because of the levels that implies near 0dBFS resulting in blowing your amp, speakers, or ears still stands though.  (Or raise your hand if you listen in an anechoic chamber with 10 dB SPL ambient or lower.)  96 dB dynamic range is plenty, way more than people reasonably make use of anyway.  These days I'll be glad if producers can make use of 15 dB dynamic range on some recordings...

Even the most dynamic recording ever released doesn't have a dynamic range of more than about 65dB, the dynamic range of a CD would be around 30 times greater. So even at -65dB there are no problems with the digital noise floor. Bare in mind that modern 16bit recordings have been created with noise-shaped dither, this increases the perceivable dynamic range of CD to around 120dB, roughly 1000 times greater than the most dynamic recordings. Also consider that most rock music has a dynamic range of less than 40dB and a most other modern pop genres often have dynamic ranges considerably less than 30dB. The digital noise floor of 16bit is well outside audibility at anything other than ridiculous listening levels.

G