Northlight Images has uncovered a patent (Nikon patent 2017-125904) for a 35mm f/2 lens for a curved image sensor. The patent does show a mirrorless application.
Nikon recently had this to say about its mirrorless plans
While details are confidential, we can say that we are currently developing new mirrorless products that build upon Nikon’s strengths, and offer the performance prospective customers expect, including the ultimate optics performance, image-processing technologies, strength and durability, and operation.
This patent could be unrelated, as many patents amount to nothing. However, Nikon is saying all the right things about its mirrorless plans.
There’s nothing new on the Canon front as far as a full frame mirrorless goes.