They are better than they were a couple of years ago but they have a long way to go still for lots of photographers. I can’t stand the electronic viewfinder on the Sonys but I’ll concede the A7 EVF is usable. The poor AF and ergonomics aren’t doing it any favours either. The images are gorgeous but what does that matter if they are out of focus? The shocking battery life isn’t a great selling point either.
As for SLTs being a replacement for traditional mirror flapping DSLRs, I think it is an evolutionary dead end. The SLT concept has very few advantages and they really only amount to having constant AF during fast action but it still isn’t an improvement on a canon 1dx. The fixed mirror means a bulkier body with longer flange distance which in turn means larger lenses than mirrorless. The mirror also steals one stop of light. To top all of this off you have to use the EVF instead of an OVF which is really only better when you are doing video.
I have no doubt the optical viewfinder will disappear in time but the tech just isn’t there yet, the 2mpix EVFs are usable but not more than that.
I would quite like an Canon EOS M but the AF is just a bit too lacking as it stands and needing to bring a handful of batteries if out shooting a whole day is not appealing. When one comes out with the 70D sensor I will get one and can then get rid of all mid sized cameras and keep a small mirrorless and a couple of big 1 series cameras. I’ve been really close to buy a EOS M with the great little 22mm f2 pancake but they never go that cheap in Britain it makes enough sense to get one.