In the same way that film developed over the years with finer detail the same will happen to sensor design . Photography is big enough church to accommodate all what ever size of sensor. Lets not forget marketing and advertising. How much quality do you really need? There a lot of FF hype out there. When was the last time a picture editor, competition judge or RPS assessor asked when looking at an image. Is it FF.? They don't because it doesn't matter, its the picture that counts.

David