An interesting speculation. It does seem that 120 roll film cameras are going to outlive 35mm film SLRs, since of the latter, only the Nikon F6 and the Cosina-produced Nikon FM10 are still on the market (and I am fairly sure that the F6 lives on only though stocks in the warehouse). But at the university where I work, I still see lots of photography students carrying 35mm film SLRs, so simple mostly mechanical cameras that be made in small volume could live on.
Another cause for optimism: so long as a photographic emulsion is still in production, it seems fairly easy to coat it in small batches onto uncommon film formats, like 5"x4" and 10"x8" sheet film, and even the more exotic sizes that Ilford lets people order once a year: http://www.ilfordphoto.com/Webfiles/20163291435591962.pdf
So I predict or hope that the artistic and hobbyist market will keep various film formats alive, even if all the professional uses move to digital.
Its not a speculation its an estimation based on the following:
1. Out of all makers that ever made a 35mm camera, only Leica bothered to make a new film release of the m camera from 2000 after (the ones you mention out of Nikon are both past designs). Obviously, Leica's release is more aimed to support Leica's image and tradition than provide profits to the maker.
2. The latest releases of Hasselblad, all support film and then there is a wide base of Medium Format cameras that are not compatible with modern MFDBs, or difficult to support, or financially unwise to do so... Much of this equipment is both capable, but makes sense as a choice for users of DSLRs as it is easily accessible and cheap to invest on if purchased S/H, but gives access to film, ability to familiarize with MF to young photographers and high resolution access if scanned. So, many think of it as an alternative as to have instead of MFDB next to their DSLRs...
3. The view camera has turned to 120 film as the major media used on them many years ago... The 6x9 cameras are the main force for all makers lines and additionally most view camera users of view cameras have added 6x7/6x9 120 film backs for them...
4. 120 film is used on many later HQ film releases from major cinema studios because of the looks and tradition...
All and all, 120 film seems a good compromise for quality/resolution, it is much cheaper than sheet film to use, not much more expensive than 35mm, easy to develop, offers much better quality than 35mm film if scanned, doesn't give away much as far as IQ is concerned to sheet film, it is easily accessible, easy to develop, it is compatible with many excellent lenses and thus makes more sense than the rest.