I don't think that there is still a debate as to whether mirrorless will overtake DSLRs from a technology standpoint. They obviously will and some may argue that they already have.
Where this is a lot less clear, it is the shooting pleasure. The enjoyment of looking at a scene through a good quality OVF remains, to me, one of the reason why I choose to spend time photographying instead of doing something else (and god knows there is a wide array of other things I enjoy doing).
This isn't about digital readiness/understanding/... it is just about pleasure.
Cheers,
Bernard
Bernard, Some time ago I would have said exactly the same. I was used to using amongst the best if not the best OVFs in the business - 30 or so years with Hasselblad V film & H series digital systems - and the viewfinders were a major factor in choosing those systems.
And then something weird happened, I acquired a used Leica M9 and fell in love with a rangefinder. The optical viewfinder was bright, expansive but admittedly not WYSIWYG. It also allowed me to see beyond the frame whilst looking through the viewfinder, something I had never before experienced or appreciated. Now I could watch people walking into the frame and make compositional judgements with ease. I was working in an entirely new way. Of course the use was limited and as much as I loved the M9 I eventually switched to the M240s to take advantage of liveview via the accessory EVF or the LCD. This change meant my system was now far more adaptable, covered all of my needs and introduced me to a new and exciting working methodology. One system, one small bag and the best lenses I've ever used: Heaven.
Now, I'm not suggesting for a moment that my choice of system is the answer to everyone's needs, far from it, it is niche in the extreme. What I am suggesting is I've forgotten all about that compulsive need I had for the best OVFs in the business; I've moved on. I still use the RFOVF most of the time but I now have the adaptability of choice.
So, how has this affected my work? Well, I feel that over the last five years my work has diversified more than I ever thought possible and as far as anyone can judge their own work has also developed and improved beyond my expectation. Why, well, obviously not because I'm using a better viewfinder, but that said perhaps because I'm using a different kind of system with a different kind of viewfinder, that different methodology and the buzz that change brings. Whatever, the change certainly hasn't hurt.
Good shooting to you.
Keith