A rumor has exploded onto the Internet. And by exploded, I mean that it is being discussed by a few dozen guys. This is the camera industry, after all.
But yes, the rumor. Sony is apparently in the final stages of development of a full-frame NEX camera with an expected reveal in 2013. If this is true, and I'm not sure that it is, I would be very disappointed. Sony hasn't done shit-all with their NEX series of cameras. The lenses are, save for one of them, sub-standard. No, they're not bad lenses, but they don't impress, and they positively fall on their face on the NEX-7.
If Sony does release yet another system, they will be stretching themselves ridiculously thin. Unless they plan on tripling their investment in cameras, which is certainly a possibility, but even then, triple your investment in your current systems. Sony has half-assed many elements of their current products, and the only thing causing me to continue my recommendation is that they have great potential. But if Sony is going to just throw out a system, not support it, and move on to something else, only a maniac would by their products!
Let's say, for the sake of argument, that Sony is indeed developing a full-frame NEX system. First, the larger the sensor gets, the more the size benefit is negated. The lenses on the NEX cameras are already much larger than 4/3, and full-frame will be larger still. We could assume that Sony will only product compact, prime lenses in the vein of Leica. But even on Leica, their more extreme focal lengths, like the 135mm, are large and slow.
Second, Sony's success with the RX1 is only because the camera is profoundly unique — a combination that is both unavailable and indeed impossible in other systems. But with an ILC, Sony will have a hard time making a good value proposition. Remember, size benefits are increasingly negated with larger sensors, and the performance of traditional, mirrored cameras will be more robust than the Sony. People with the cash to buy a camera that will undoubtedly cost as much as the FF-NEX would find a purchase hard to rationalize. Holding up Leica as a counter to this argument doesn't hold water, since Leica's sales are mostly due to the Leica name. Sony has no name, at least not in the photography world.
Third, Sony will now have another system that will need lenses. They've already shown little interest in developing the lenses in their current NEX line, and they're not doing too well with their APS-C and FF SLR cameras, either. Will they simply pop out an adapter for their current A-mount lenses? All that will do is further negate any size advantage, by adding a huge, honking adapter along with large lenses. WTF?
I will be very disappointed if Sony releases this. The thing that kept me from leaving 4/3 for Sony was its pitiful lens selection, and this seems to indicate that they won't bother with lenses anytime soon.