So what about the Sony A7/R compared to my needs?
Image quality - check. Excellent. Confirmed by the first reviews already. Best sensor in the industry [no, it is not behind the D800

]. Highest resolution and best DR ... at least up to ISO 3200. Yes, I do use and need Hi-ISO a fair bit, but only up to 3200, very rarely to 6400. So don't care for 51200 or more. Cudos to Sony for putting that sensor into such a small package!
Lenses? The good: SonyZeiss 24-70 has in-lens IS ("OSS"), CaNikon has not. If the SonyZeiss turns out to be as good as expected, it would be my pick and cover 50% or more of my shooting situations - both in focal length and in max. aperture. And it will still be way smaller, lighter and less obtrusive on an A7/R than the CaNikon behemoths on a 5D III or D800.
To really "go light" I'd want 3 ultra-compact moderate aperture "pancake" primes. Most of the time I would only carry one lens on me, depending on intended photographic target/shooting situation.
a) W/A landscape and confined space pancake ... ideally a 18mm/f 4.0
b) normal view pancake - ideally a Sony FE equivalent to the tiny, "good enough" and dirt cheap Canon EF 40/2.8 [which I have and like]
c) a portrait lens - ideally a compact 85/2.0 WITH stabilizer. Sizewise like a Leica M
One more thing: I'd love to get these native primes without manual focus ring & gear - so as "purely AF-versions".

Makes 'em smaller, lighter, cheaper and easier to wheatherseal. I am never focusing manually anyways. Sony is not there yet. 1000 USD/Euros for a 55/1.8 are a bad joke. No matter whether it says Zeiss on it or not. But I am confident, Sony will get there fairly soon.
My biggest area of discomfort: I think the Sony E-mount really is a bit too narrow for FF. In combination with the very short flange distance of 18mm it restricts opportunities to design very good, fast lenses at affordable prices. A mistake they'll not be able to correct.
Stabilizer: Sony really, really should have continued their strategy of putting a sensor stabilizer into their cameras. Even if it had added a few mm to body size and another 100 bucks or so to price. One of the serious drawbacks in my view on the A7/R. But maybe they'll put an Olympus-style 5-axes stabilizer into the A8/R.
Autofocus: big question mark. One-Shot probably OK for my needs, even on A7R. Tracking AF likely not yet, even on A7 ... and even for what I expect: people moving at medium speed [not indoor ball sports, not cheetah pursuing impala, no birds in flight or similar]. Unfortunately Sony did not get PD-AF on the A7R sensor. Again, maybe A8R. What I consider "good enough" is exactly what Nikon 1 AF or Oly OMD 1 deliver. Will test it when I can get my hands on an A7/R where I live.
In terms of fps I am happy with anything between 4 and 6 fps. I ain't no "machine gun Joe". 7D is overkill for my needs in that department.
Shutter noise: A7/R ... need to test myself ... but almost certainly "fail". This really bothers me a lot. I do a fair bit of shooting at (classical music) concerts, theatres, in churches etc ... and also a bit of street photography. Silent operation when needed is one of the major attractions of a MILC-system to me. Oh well, maybe A8R. Make it a mech-free shutter please. Electronic global shutter. 100% digital camera.
Battery charge: absolutely disappointing. 200+ shots is not nearly enough. Sony should have added a bit bigger grip to take the regular Alpha battery NP-FM500H with 12 Wh charge. Or a new, better battery. Again, maybe in the the A8/R.
Flash ... probably fail. While Canon is not quite there either [e.g. no 2nd curtain sync and no zoom-head control in wireless operation, not even with RT-gear; no 430EX-RT, no RT-receivers to enable radio wireless on existing 580/430EX IIs] they are clearly ahead of Nikon and way ahead of where (I believe) Sony is. Probably there are and will be third party triggers available, but they are always a far cry from a good, "native" flash system. I have no intention to buy pockewizards or China-stuff when all this flash functionality could and should by all means be built right into the gear from the start. Sony really needs to step up their flash-game. AH yes, I would also like to have a pop-up flash for fill in the camera. It helps me to go light, without a speedlite, when only a little fill is needed.
So - in total more question marks at the moment than thumbs up. But I'll check the A7/R out sometime soon. And I am sure my 7D will easily last me another year if need be.