Yesterday, Nikon announced that they are developing a new Nikon full frame mirrorless camera system with a new lens mount, the official announcement will be on August 23rd, 2018. And rumored release date in late September to early October.
Many people are asking about when will Canon announce their full frame mirrorless camera, according to CanonFF, Canon is also developing full frame mirrorless camers, and first Canon full frame mirrorless camera will be officially announced in the second week of September. The Canon full frame mirrorless camera will be shown on Photokina 2018.
You can take a look at rumored specs of Canon full frame mirrorless camera here.