Maybe, but then these workhorses are usually more rugged, better weather-sealed, have more battery capacity, and in LiveView mode the sensor can equally well see the optical/projected image, and employ whatever technology is suited then.
And that's something I wish Sony would address - a tougher, more powerful all-round mirrorless camera, built around the same great sensor they've developed.
Thing is, it's not an inherent advantage of the D4, 1Dx, D810 or 5D3 - there's no special technology which makes them that way. It's just a matter of size, and something any manufacturer could add if they so desired.
Features like expose on subject movement, or contrast or on-sensor phase detect focus, or eye focus, face detect and whitebalance, or, ...
All of which requires it to operate in live view mode, where you lose the advantages associated with it being an SLR in the first place, can't hold it up to eye level (i.e. needs to be on a tripod, since you can't realistically hold a D5 with attached lens out at arm's length and keep it steady) and still doesn't use them as well as a native mirrorless camera (due to the lack of an EVF to amplify the advantages of those things).
And it may raise the resolution bar,
This is probably the best thing it can do.
I see three major breakpoints here - 32MP, 36MP and 54MP.
At 32MP, you have the potential for 8k video. For an action/journalistic camera, that's a very big thing with regards to utility and futureproofing. Go on a wildlife shoot and take some stills and an 8k video sequence all in the same shoot. And, with the battery and processor power of an improved D4-type body, 8k video is probably doable.
At 36MP, you can do a 1.5x crop and still end up with 16MP - a very respectable total which greatly adds to the utility of the camera when shooting wildlife or sports at long distance, where, even with long lenses, you're often focal-length limited and have to crop. It's like having an inbuilt, 1.0-1.5x teleconverter - sacrifice some image quality to have the subject take up more of the frame, and, at 1.5x crop and 16MP, you still end up with acceptable quality. At this resolution, you've effectively got a FF and crop body at the same time, with all the composition advantages of having a bigger frame to play with.
At 54MP, you'd be able to get a 1.5x crop of 24MP - equal to the best crop bodies on the market today.
I'd say a significant increase in resolution (with pixel binning for those concerned about file size and who don't need to print large or crop heavily - which also eliminates moire and colour aliasing artifacts as a side-effect) would be the best thing they could do in a D5 while still retaining an OVF and mirror.
or add 4x or more multi-sampling capability for higher (color) resolution with reduced aliasing
That would make much more sense in a D820 than a D5 - if you're after resolution and reduced aliasing and your subject doesn't move, why would you go for an action camera with the lowest-resolution sensor Nikon offers, instead of the camera with just about the best IQ on the market at the moment?
Add that technology to the D810, however, and you'd have a beast for product photography.
Maybe, if not patented, it can employ sensor tilt and shift
I'm sure Sony's already patented that, given that they were talking about z-shift focusing a while back.
In any case, it would be unusable outside of live view, and, hence, would make little sense on an action camera and much more sense on a mirrorless body (or, at least, on a camera like the D810).
