I thought the problem was likely solvable, and it appears it is in Photoshop.............
The point was that increasing the dynamic range of a digital camera to 12 stops would not represent an alternative to correct exposure any more than 12 stops of B&W eleminates exposure problems. It provides more latitude to get acceptable results, but not a fix. Variable contrast printing paers can cover up some exposure/developing problem, but not fix them.
To get the results you expect, there seems to be little alternative to correct exposure
You seem to be contradicting yourself here. You agree that the problem is solvable with PS and then go on to say that it's not really solvable.
Variable contrast printing is not so relevant in the digital world since the source can be adjusted to suit any type of paper.
However, there could still be an 'expose to the right' issue even with a camera with a 12 stop DR. Perhaps this is what you are referring to.
If we take the example of the indoor scene with a view out the window; an evaluative, automatic exposure with current DSLRs would severely overexpose the view through the window, blowing lots of highlights, particularly in the sky, and would produce a perhaps more reasonable but still underexposed interior.
Neither part of the image is going to be correctly exposed. You might be able to recover a significant amount of detail in the clouds (if there were any), but the blue channel will be severely clipped and the sky, if it was blue, will range from grey to sickly cyan.
The interior will exhibit lots of noise due to underexposure. If too objectionable then Neat Image will help, but the result will still be slightly degraded. In fact, the image over all, after extensive processing, will be somewhat degraded.
Supposing the camera were capable of 12 stops DR. The interior part of the image would then look as though it had been shot with a current 6 stop DR camera exposed to the right, and the same for the view through the window. Essentially, one would have two images, the interior and the window, both of which would look as though they were two separate but correct exposures taken with your current average DSLR.
You could argue (and I wonder if this is your point), if the view through the window was irrelevant to the composition, then one might choose to expose the interior fully to the right of the 12 stop range in order to get more levels. However, I doubt there would be much advantage in this. I suspect any future 12 stop DR camera will only achieve such a spectacular DR by compressing the brighter values; ie. it would not be a linear imaging device like current cameras.