While Sony didn't announce any large sensor cameras at NAB 2013 as some had speculated, they did show off some concept 4K DSLR-type cameras with heavy-duty positive lock mounts (only one of the cameras actually takes standard PL lenses, the other is an A-mount) that may or may not find their way into the hands of shooters. Even though they are far from completed cameras, they do speak to where Sony may be looking for the future. Check out this video below from Engadget, who was at the Sony event where these were being shown:
While I think form factor is important, and has probably been part of the reason for Canon's success with C300-style cameras, lenses are a big reason people have flocked to those cameras. Certainly it's nicer hand-holding a camera like the C300 than the Sony FS700, but native support for Canon lenses makes a lot of sense when you're appealing to a crowd who is comfortable with shooting video on DSLRs. That's why it would be very interesting if Sony decided to make a 4K camera line in the DSLR form factor. I think they would have an uphill battle in terms of lens compatibility because Canon lenses are still more popular, which is why the E-mount might actually be a better choice for a camera like the one pictured below. Plenty of adapters are made for the Sony E-mount to other lens types, including PL, and Sony even makes their own E to A-mount adapter.
You don't have to look far to understand why a company would want to make their cameras more compatible to other lens types. Blackmagic heard the calls for an MFT mount on their 2.5K camera, but there is a reason the first model they introduced had a Canon mount, and why the new 4K camera also has a Canon mount (I believe it will get PL eventually). While it's a lot of speculation, especially since these are just concepts, the 4K DSLR is definitely interesting, but if they want to compete with everything Blackmagic is doing, they are going to have to give users a reason to consider their camera, and 4K will not be enough -- they'll also have to compete on price -- and at the lower end of the price spectrum, more lens compatibility is certainly better.
Both of these cameras are a long way off, and from people I talked to at NAB they may not see the light of day in their current forms (the octagonal camera is definitely an interesting shape), but I would actually like to see something small that shoots 4K from Sony (and is priced somewhere near their current DSLR/SLT line). I think it would be great to see Sony use the same compression as they are using in their higher-end F5 and F55 cameras, as that would help a lot with compatibility.
What do you guys think? What would you like to see from Sony regarding 4K cameras? Do you like these form factors or would you want something bigger?