Another thought.... While I would like to see is current lenses completely compatible with a new body design. If not that, at least a bridge device to make current lenses usable on a new body. However, if such a bridge device contains glass then it will likely impact IQ. The least desirable is complete incompatibility.
But if complete compatibility is not achieved, the market for used Nikon cameras and Nikon Mt lenses will be impacted, probably significantly.
I'll throw in another wrench, albeit a tiny one. Dust on the sensor will likely become a bigger issue since right now the mirror protects, at least to some extent, the sensor from dust.