This discussion is much like discussing the term "broadband". Does it mean >640kbps? Does it mean fixed pricing? Or does it just mean "whatever speed that 30% of the users cannot afford at any time"? I am sure there are government agencies spending lots of man-hours trying to define the semantics, but in the end, what matters to me is what speed/characteristics I have, not what it is called.
I believe that HDR, in this context, as others have said, only means "more dynamic range than usual". There are/will be camera sensors that claim to do single-shot "HDR" (due to high native DR), no matter if it is saved to 14,16 or 24 bit integers. Exposure stacking is no direct consequence of "HDR" but an indirect one: if you want to capture better DR than usual, you may have to use unusual methods (ie stacking).
In the end, what matters most to me is that the recording device is capable of faithfully recording scenes whose dynamic range cannot directly be appreciated on todays LDR display and paper. This means that the high recorded DR can be used to:
1. Do image processing on a "linear" recording of the scene (even if the final output is clipped to LDR)
2. Postpone choices about exposure to post-processing. The LDR window can be moved up and down according to taste.
3. Fancy tone-mapping algorithms can be used to try to squeeze the impression of HDR into the limited LDR display/paper
4. The scene is captured for posterity (and possible improved display/paper tech)
I believe that fancy tonemapping algos is trickling into regular single-shot raw developers, therefore it may make sense to use the word "tonemapping" for that kind of operations.
-h