I think digital medium format will be around for at least another 5-6 years. Unfortunately, film medium format has died largely because of the availability of film rolls. Even back in the 70's when Kodak announced it was going to discontinue Kodachrome 25 & 64, it sent shockwaves thru out the photography community. I don't believe anything has been invented yet that equates the image resolution and color depth of those two films, especially K25. Film used halide crystals in a random pattern. Digital IC sensors lack this randomness and could be one important reason why they produce lesser quality images.
I used to shoot with a Mamiya 7 MF camera and got some superb images using Fuji film Astia and Provia. But the film stock was secondary to the quality of the lens. I just don't think we have quality lenses being made today. Most of them are slow as molasses.
In the late 90's Olympus came out with their E-10 digital camera. It featured a huge and fast zoom lens, something like a 2.0-2.4. Unheard of today. And this camera was only 4 MP. But the quality of the lens allowed you to get spectacular images that I swear rival the latest offerings.
I know your post was specifically about MF - so let me say that as long there are people who are willing to use this system and can afford it - it will be here. I seriously doubt whether the average person can afford the new Hassy's - upwards of $40,000 - that's a car and it used to be three homes back in the 70's. No doubt high quality cameras were more affordable to the working pro than they are today.
And while I am on the subject, there is talk about digital cameras becoming extinct because of smart phones whose sensors are becoming more and more advanced. What do you think about this?
As a working professional, I can tell you that digital cameras essentially killed the wedding photography business as a general rule. Sure there are couples still willing to pay for a professional, but that person has to offer something of greater value than before. In the 70's, many people did not own a point and shoot. So it was easy to come in with medium format equipment and blow everyone away with quality work. Now digital P&S are so small you can carry one in your shirt pocket and whip it out and get an acceptable picture.
Finally, let me say what I have been preaching for decades - that the camera equipment does not make the picture. The person behind the camera does. Give Mr. Spielberg a five dollar and forty year old Super 8 camera and he will make you a movie that will blow away anything made on the the latest pro video cameras used by wanna be filmmakers. In short, you can produce outstanding images on any format if you know what your doing - if you know light, shadow, camera angles, etc.