I would not be surprised if eventually Fuji wound up owning Panasonic's ILC business.Today there is no compelling reason to go mirrorless. Any weight advantage from removing the mirror seems to be negated by heavy lenses. Lack of lens choice currently hurts Canon and Nikon - some what Sony also. Micro 4/3 is small but has technology disadvantages long term. New "medium" format offerings are slow to sell and limited lens choice. Sensor technology is about to take another jump - commonplace 50mp, 65,90 and 100 mp sensors are becoming available and the biggest drawback is a processor (or processors) to handle the data rates. Smart phones have effectively killed smaller cameras and satisfy the photo needs of a majority in terms of convenience and image quality. Declining market will make R&D expenses harder to comeby for even today's profitable camera manufacturers. Look for fallout from even today's "premier" manufacturers and you may find a market with Canon, Sony, Fuji and Panasonic as the only reasonable players,
The acceptable circle of confusion for a particular use case is determined by the magnification involved in that use case that occurs between the image projected by the lens onto the imaging plane and the final display size viewed from the final viewing distance by a person with an assumed acuity of vision.circle of confusion is then aperture or magnification?