I think the FF bodies compete with the Medium format stuff whenever the movement of their orbits brings the pixel counts close and prices closer.
So when all of them were stuck at 39MP max, and Canon had 21, FF 35mm made some ground. Now that the 35mm stake hasn't moved much, but the medium format has jumped to 60MP, things widen some. Of course the prices on both have dropped (hassy price dropped). Where the medium format dies is ZD range. No one is going to buy a 20MP ZD for 10,000 when they could have a 24MP A900 for 3K (probably 2500 soon) and a bunch of Zeiss lenses. As long as Medium format can open up some pixel ground and not go crazy on cost, they will manage. Not sure how Leica will manage, since they have something more ZD/645D like, at a much higher price. Still 20K is less than A P45+ or their new 60MP back and those rigs don't have a body. So many they will hit a nitch (until nikon comes along and does the same).
This is where I think Sony is blowing there changes. If they had a full range of Zeiss lenses that would target medium format folks, they could make some ground. Look at the lenses Leica is bringing. With the FOV equivlant in 35mm, with what that lens will/should be for Sony.
24mm = 19mm -> 20mm ZA
30mm TS = 24mm TS -> 24mm ZA TS
35mm = 28mm -> 28mm ZA TS
70mm = 56mm -> 50mm ZA (yeah, close enough, and sure the 1.4/50 minolta might do the job, or the macro)
30-90mm = 24-72mm -> 24-70ZA SSM (Done)
100mm = 85mm -> 85mm ZA (Done)
120mm macro, 96mm macro -> 100mm macro (done enough with the old minolta)
180mm = 144mm -> 135mm ZA (Done)
350mm = 280mm -> 300mm (well, there is the G, but maybe a 4/300G would be more like it).
So, they basically made the lineup Sony should have had for the A900. On the top end, they got it. But notice where Sony blows it. Everything prime below the 85mm. Now many could argue the 16-35ZA does they job. Ok, but notice the major one Sony missed, the tilt shift, the lens that makes the most sense for a mega-megapixel camera, a whole line of them. The main users of such cameras are the main users of such lenses. Canon has had them. Nikon has now got them. Hassy has added their adapter for them. Maymia-Phase one is bringing one. Rodenstock is bringing a line out for Canon and Nikon too. Everyone is realizing it's a critical thing to have as Film is dead, thus view cameras are dead unless you have insane piles of cash for a digital rig with a phase one back. Sony had what was clearly 2 wide angle zeiss prime mockups, where did they go. That's what the need too. Sony should be doing everything to make the A900 a medium format replacement. An A900 plus a pile of ZA lenses. You could buy it with all 4 full frame ZA lenses and be under 10K which is what a ZD body cost, no lenses.