According to one statement from Sony, they are not announcing any medium Format mirrorless camera anytime soon but they could do it. In a recent interview with Photolari Sony Claims that “developing a medium format system requires Time and Resources plus when you are entering into a new system branch means you also have to develop new lenses and accessories”.
On the other hand, you should know that Sony 100MP and 150MP BSI CMOS Medium Format Sensors are in regular talk, which were expected to be announced at some point of 2018. But this current statement from Sony perhaps says us to hold our fingers crossed and be happy what Sony is seriously developing with i.e. Full-Frame system!
Via – Photolari