The reality is IMHO that the push towards mirrorless was mostly the product of Canon and Nikon coming out on top in the move for the DSLR market. Everyone else either needed to look elsewhere for significant market share or fall going to the wall (or becoming a niche player).
I think there's much truth in this. Innovation is often driven by the simple need to stay alive. But it's not the whole truth. The move towards EVFs would be happening regardless, though probably not at the same pace. The benefits are obvious to anyone who uses them without preconceptions of the "optical VF experience" being superior. (Sports & BIF photogs excepted…for now anyway.) The benefits are also obvious to the various camera makers in terms of reduced mechanical complexity & manufacturing costs. I imagine CaNikon will be using EVFs in lower-end SLR-like cameras before too long*. How fast they migrate upwards in the product line will depend on how well they're received by lower-end buyers…and how much of a ruckus is raised by the Reflex Forever!
*Another possibility, though, is that the mirrorless market may in the short term discourage
CaNikon from using EVFs in EF & F mount cameras, despite the benefits, in order to better differentiate themselves from that market.