Please cite some form of numbers or non anecdotal evidence for this. It's said here often but the only actual evidence in aware of points to a different story.
If you look at Team Phase One revenue - which is public record - it is up year over year since the Great Recession 8 years ago. Nearly every day we hear from someone that is a small format shooter looking to get into medium format for the first time (in addition to those who are upgrading an existing medium format solution).
I'll grant you my point of view will have an inherent bias; I'm more likely to speak to someone moving from small format to medium format than vice versa, but the public sales numbers would seem an objectively fair place to look.
Doug, FWIW I am a medium format proponent.
Much of my industry (fashion) is downing medium format for the Nikon D810 and more recently 5DS R. I mean people at the very top like Peter Lindeberg, Craig McDean, Glen Luchford, Steven Meisel, to shoot the most lucrative and relatively significant mega brand campaigns such as Gucci, who have always traditionally needed and demanded max IQ. These people are a barometer of the industry and have a further influential effect over the industry.
If you want non anecdotal evidence, go look at something like Interview magazine and read the metadata of images, where it is plain to see that instances of medium format, or anything over, or younger, than a P65 are very rare.
I am not wishing doom on anyone, but I can not personally see how Medium Format Digital can last without some serious innovation/evolution/revolution something of substance beyond marketing and numbers.
