This whole Nikon WB, ACR and DNG issue has annoyed the h-e-l-l out of me recently, and after your publishing of Jeff Schewe's comment I felt I had to give my opinion on this.
Whilst I don't think Nikon are being particularly helpful in this matter, I don't see that Adobe are so far being much better either. Currently Adobe are hiding behind DNG and trying to position themselves as doing a great favour to the photographic community by almost trying to bully Nikon into adopting it.
It strikes me that the people who stand to gain most from DNG are Adobe. They're obviously feeling the pressure of their decision to reverse engineer RAW formats as the camera manufacturers continue their onslaught of new models. IF everyone adopts DNG, this problem is largely solved for them. However looking at Mr. Schewe's comments I'm not convinced that DNG is the answer, or that the posturing of late by both Nikon or Adobe shows any sign of progress being made in the area of RAW formats.
In JS's quote he says "Nothing in the file should be in any way undocumented or in any way restrict the access to the image data by the author of the photograph." Now I know JS doesn't work for Adobe, but it seems Adobe have already broken this rule with DNG. They have put with CS2, application specific info into the DNG, which can only be read by ACR (and understood) and I doubt very much if any of it is documented.
Also in February Adobe updated the DNG standard to 22.214.171.124. Whilst they didn't start writing files to that format immediately, their software that was released at the same time, already used some of the new format tags and would read files in the new specification. Is this really an open standard? Strikes me that other software vendors are at a slight disadvantage here if the first time they see a DNG change is after Adobe have already implemented most of it. Surely for a true open standard everyone should get to see the proposed changes at the same time to create a level playing field.
JS goes on, "The raw file must belong solely to the photographer with no lien or encumbrance attached in any manner, what so ever." Pretty strong stuff, so, if Adobe are already dumping ACR specific metadata into DNG files, who's to say the rest won't follow? Do we really want a RAW file format that if processed in several different converters starts to accumulate application specific metadata on it's travels?? Not sure I do.
Of course, once you have a standard RAW file format, Adobe seem to lose interest quite abruptly. I'm sure Michael's workflow is not an umcommon one, convert RAW file, adjust in Photoshop (or some other application) using adjustment layers so that changes can be easily reversed. Save huge file to an open industry standard format that is fully documented as surely the image still belongs to the photographer right?? Oh, hang on, save to PSD, not open. But hey, that's OK, locks people into Photoshop. layered TIFF's are a bit of a crap-shoot support wise as is compression within them.
Next step is to create an output specific file, for print or for web or for whatever. Web isn't too much of a problem as JPEG's pretty standard but if you want a finished file without lossy compression, then TIFF is the only option but again it's not quite there. What format is best here? Not clear to me what final format will still be around in say 50 years time.
So, I'd say that DNG alone (or any equivalent) is not enough. We need:
1) A standard RAW format
2) A standard editing format that allows saving of layers that is properly supported.
3) A standard final format that is properly supported.
So whilst the camera manufacturers are clearly lacking so far on number one, the software companies haven't done a much better job at number 2 & 3. Yeah I know TIFF-EP is out there but how many times have we seen a complex TIFF written in one appliction cause another to choke??
I'd say no-one is whiter than white here and as users we shouldn't be concerned just with RAW formats because the latest one isn't supported in our software, we should be concerned with the whole end to end life cycle of our files. I also think any industry standard should be proposed by the industry as a whole and then owned by an independent standards body. Can't see that happening yet and as a result I'm not sure the manufacturers will ever buy into DNG.