The reason i give a rather modest time estimation is that i have heard the argument "film is dead!" so many times over the years that i know it simply wont go away. I have an article from Variety from 1980 which proclaimed "film is dead!" in light of the recent video developments being made, such as the high quality Beta format. In fact in the 70's this argument was made as well. Then in the late 1990's as HD cameras were first being introduced the old argument was brought out: "film is dead!" Well no--here we are many years later and not only is film not dead it is stronger than it ever has been. Kodak's sales of 35mm motion picture stock are higher than they ever have been in the companys 100+ years of existance, and more productions are out there shooting on film than ever before. There is also the fact that many people simply wont want to switch to HD, simply because they can do the same thing with film, only better--i don't expect Roger Deakins to ever contemplate shooting something on video, no matter how good the developments get.

And this is a large part of the issue: sure, HD will one day be able to emulate film with 95% faithfullness--but film is film, with 100% faithfullness; as technology develops and HD prices go down, so too does film-to-digital prices--a 2K DI is now affordable and common for indie films, whereas in 1999 it was extraordinarily expensive. So if a low-budget production can shoot on film, theres no reason why a big-budget studio production cant. There are so many institutions and companies well-ingrained in the film world that cater to the actual film market that even if HD comes out with a 6K perfect-looking camera these companies and inviduals are not going to go away over night; political and economic factors play a big role.

And yeah, the digital still growth is quite impressive--but a lot of professional photographers still don't use digital cameras unless it is for sports and news type of shooting, where the speed, cheapness and ease-of-use is a welcome tradeoff to the lost quality; for professional photographers of any other kind, ie fashion, the majority of them use 35mm film, and for the really high-quality shoots they have to use medium-format film because not only can digital get nowhere near the resolution, film simply looks better. When will we see digital equivalent to medium-format cameras that offer the same image characteristics? Probably ten years, plus another five or so for professionals to make the transition. When you consider that digital still has been around since the late nineties, this makes a thirty year development period, which is about the same as i estimate for motion pictures.
In motion pictures the process that you talk about in the consumer digital still world has already happened as well. Look at the camcorders on the market--they are all either miniDV or DVD. I havent seen Hi8 or 8mm or VHS or VHS-C sold for a long time (although if you look hard you can still find them). Low-budget and no-budget filmmakers also shoot on DigiBeta, BetaCAM, DVCAM, MiniDV or any other form of DV SD videotape because the ease-of-use, speed and inexpensiveness is an acceptable tradeoff for the level of work they need it for. HD is in this category as well--in fact, HD cameras were designed with documentary use in mind, which is why the Sony F900 resembles the long, news-style shoulder-mount cameras. The Arri D-20 that i believe hasn't even come out yet is really the first HD camera designed with dramatic motion pictures in mind.
Really, the so-called HD revolution hasn't begun yet because all the efforts thusfar have been the equivalent of low-budget filmmakers picking up camcorders and news cameras and making movies with them.