I welcome the day when E.V.F. equals then surpasses our mirrors & prisms. There are some huge advantages to e.v.f. . We are getting closer but not quite there yet. When it equals & surpasses what we have presently - great & good but until then no thank you.
Better yet just let me wi-fi stream everything to my contact lens overlays and I'll be as happy as a pig in §π¡±.
Generally speaking, an optical view finder (OVF) will always be superior to an EVF in certain ways. For one there is little to no limit on the amount of detail or amount of light you could observe through an OVF. EVF's, being small digital screens, will always have certain limitations...on dynamic range, on resolution, on response time. Their small size is both a benefit (allowing the use of super cutting edge screen technology that costs a lot without it costing too much) while concurrently being a detriment (you can only do so much with so little space). We don't notice the limitations of a beautiful AMOLED screen on our smart phones because we observe them from an average distance of 10 inches...however when the same kind of screen is a mere inch or two from your eye, its limitations and flaws will become readily apparent. The key limitation that I think will always prevent EVF's from "surpassing", and possibly even equaling, an optical prism-based viewfinder, is dynamic range. With an OVF the only limit is your eye (i.e. you couldn't and shouldn't look at the sun through a camera)...however you could look at a very bright sky, and still pick out detail in the shadows with a little bit of focus. An EVF, even one using technology years from now, will never be able to offer that much dynamic range...something will have to give. You'll either get blown highlights, or lack the ability to see detail in the shadows.
There are also the inherent lifespan problems with an electronic screen...OLED devices use organic substances that have limited lifetimes. Even inorganic technology can burn out, either at the pixel level (leaving you with a dead or stuck pixel or pixels) or simply dying entirely. How many times have you heard anyone say they couldn't use that 50, 70, 80 year old or even older camera because the view finder was burnt out? Never. An optical device will last forever, so long as it doesn't receive enough shock to break it.
I think the DSLR could be improved in one primary way. Since they use electronic sensors, I don't fully understand the need for a shutter. If we drop the shutter from DSLR's, that leaves only the mirror itself as the last mechanical component that could possibly wear out from extended use or age...and they are (and have always been) easy to replace if necessary. An electronic shutter could open up new avenues for DSLR's as well.
I find the newest EVF's to be really good and I wouldn't mind using one. I can already see the composition really well and I don't think you need to see insane amount of detail and DR through your viewfinder. EVF's can provide more information like a histogram and a electronic level. Also in low light condition evf's are much brighter.
Camera's can't last forever anyways. Because of mechanical wear, camera's are rated a limited amount of clicks , for example 150 000. An EVF can actually limit the amount of mechanical wear. OLED's last about 14000 hours. Assuming you look a minute (which I think is really long) trough the viewfinder for each shot, the evf will last you 840 000 clicks.