When Olympus came out with the four-thirds concept integrating a smaller body, smaller sensor and smaller lens, it made sense. They wanted a small light weight camera for people to easily use.
While quality from those cameras are good, maybe they can’t compare to the bigger APS sensors. But the four-thirds quality has been improving in leaps and bounds.
Sony is now making an even smaller camera body, and I think using a APS sensor. But they are not making smaller lenses, i.e. a whole new breed of camera. To me that kinda defeats the purpose. You cannot use the NEX body alone. You need the lenses which are big compared to the body. So the goal of compactness is only half achieved.
If Sony or other manufacturers can make a smaller sized sensor with quality as good as current APS or four-thirds, together with corresponding smaller lenses then I think that would be more revolutionary.