I just bought an R8! Probably still the right call with an EVF, unless it has precapture and an optional EVF. I should know better.
I can't even count how many times I have been very close to buying an R50V, only to decide "not today, maybe when they come up with an external viewfinder". And so it is. Still no R50V in my bag.
I think making EVF-DC2 compatible with R50V (and other upcoming small V cameras) wouldn't be too difficult, if the Canon engineers are not planning anything better. If they are, I hope they publish it soon.
A cool feature would be if the viewfinder was "turnable"; instead of just looking through it behind the camera, like you would through a normal viewfinder, the new external one could be turned to point different directions. Pointing it upwards would be very beneficial while shooting anything on ground level or near a wall or another similar obstacle. Yeah, you can turn the screen. But it is never as good as a viewfinder, in my opinion. And yes there are big viewfinders that can do this, but they are way too big with something like R50V. It would have to be something in the size class of EVF-DC2. One can dream.