If I had a few hours I'd go through the archives here and pull up every time someone has predicted the death of MF. If you lived in the world of the forums you'd have thought MF died when the Canon 1D was released, then when the 1Ds II was released, then when the 5D2 was released, then when the D800 was released.
Funny thing: each of those cameras were released and people keep buying medium format. It's been a great year for us.
I think what most people don't get is the numbers. If MF doesn't make sense for you, that doesn't mean MF will die. MF was always a minority in the global camera market and MF has been certifiably a niche market for nearly a decade. It doesn't need 10%, or even 1% of "photographers" - it needs a sliver of the market.
This aside from the government/institutional/scientific/industrial applications which are small in the global-camera-market sense but huge markets for medium format.
Plus in addition to the image quality benefits there are many technical, aesthetic, personal, ergonomic, and emotional reasons to buy a MF system:
- large and bright viewfinder***
- touch screen interface (some bodies); hard to find a system you can check 100% focus on faster on a specific part of the image than an IQ or Credo
- tools like auto-horizon and auto-keystone which correct the level and pitch of the image in software based on the electronic levels in the back, making every horizon straight and every vertical parallel without manual tweaking
- Flash sync speed with standard strobes rather than dinky flashes (up to 1/1600th)
- More tactile lens response when manually focusing (large focus barrel, actual lens gearing*)
- aspect ratio (some prefer 4:3 or 1:1, especially for verticals)
- waist level viewfinder (some bodies)
- ability to shoot vertical without rotating camera (some backs)
- low ISO without ND filters (useful for dragging shutter in some styles)
- ability to shoot film with same system as digital (some bodies)
- ability to turn sensor on/off independent of the shutter/flash firing (allows to build up exposure with strobes without excessive ambient light, even in bright conditions e.g. interiors)
- ability to crop a vertical and horizontal from the same frame (even 36mp in 3:2 is not enough for many applications when cropped to a vertical)
- ability to use on specific legacy cameras (some folks just plain love Contax, Hassy 500)
- ability to use on speciality equipment like Aerial, industrial, art-repro systems (obviously a niche)
- ability to use on tech cameras like Arca, Cambo, Alpa
---- rise/fall/shift/swing/tilt on every lens (if IC allows)
---- fully mechanical/traditional shooting
---- extremely precise focusing for specific distances (some bodies)
---- extremely precise focusing for hyperfocal distances (some bodies)
---- absolute best glass, period
---- ground glass (some prefer it regardless of other options)
---- small/light pack size for a body and several lenses (depending on which body and lenses of course)
- compatibility with view cameras
---- close focus possible with many lenses, not just select macros
---- rise/fall/shift/swing/tilt on every lens, not just select TS lenses
---- ground glass (some prefer it regardless of other options)
- less frequent updates required to stay competitive in image quality (we still have many happy studio shooters using H25 backs users, which at base ISO and in the studio easily beats a 5D Mark 3 which is many generations newer; I don't know many happy Canon 1D shooters)**
- longer software support (original Phase One Lightphase from 1998 is still fully supported tethered in OSX 10.7 and Capture One 6, while the Canon 5D from 2006 isn't even officially supported tethered in LR4 or EOS Utility in OSX 10.7, nor 1Ds II in Windows 7 64 bit)
- consistent shooting speed; an IQ or Credo can maintain it's frame-rate indefinitely with a fast CF card, any Canon/Nikon can shoot much faster but unless you restrain yourself you can easily hit a buffer and the camera won't fire when you think it should. The IQ or Credo will be slower (around 1.2fps for the 40mp model) but it is reliably consistent - you know when you can shoot next and can develop a rhythm.
- larger bodies (for some this will be a big negative, but for others their hands are simply too large to comfortably use a camera like the D800, even with the optional vertical grip)
- differentiation: like it or not, fair or not, some (both pros and enthusiasts) will want to have a camera that Uncle Bob does not own, and that Art Director John doesn't use as their point and shoot.
- longevity/durability: some backs are built like tanks and have no moving parts. Anything can break, but the number of field-failures on a P1 back are very low.
- interesting lens selections with unique looks (e.g. Mamiya 80mm /1.9, Zeiss FE 110/2)
*As opposed to e.g. the Canon 85/1.2 with fly-by-wire focusing and a dinky focus barrel
**This is not just a question of cost since of course the 1D owner could have updated to a 1DsII and a 1DsIII and spent about the same; some photographers just dislike the hassle of switching cameras - new batteries, new chargers, new cables, new settings, new button locations, new software, new look (forcing them in some cases to expend time/energy getting the new camera to produce the look of the old camera). Some photographers love getting new gear, some despise it.
***I never understood why this isn't mentioned/discussed more often; you have to look through the viewfinder for nearly every frame you take - it's your portal to the world you are capturing.
The thread is titled "the end of medium format?". My answer is no.