I am hoping that there is one more OVF pro camera coming before the jump to EVF.
Canon would always introduce improvements in the consumer cameras first (Anyone remember the T-50, T-70, T-80 and T-90? All development predecessors to the EOS line of cameras and not all successful cameras, but the T-90 was fantastic, and a great workhorse camera for me, along with my older New F-1's), and after working out the details, would introduce them in the pro cameras (EOS-1 built on the success of the T-90). I seriously hope that Sony takes this approach with the a900/a850 replacement camera. Unfortunately, I have a feeling they will jump in with EVF before it's ready for prime-pro-time.
I switched from Canon (after having used Canon for close to 30 years!) because the OVF of the a900 was superior to any camera that Canon currently had, or has had as an offering for over a dozen years. What a refreshing camera to use (a900).
If Sony doesn't realize that many pros consider that to be one of the greatest differentiators of that camera, they may lose all the converts back to other systems by proving that the Sony solutions in the a900/a850 was a flash in the pan rather than the first in a line of consistent quality pro level products that builds on previous models. I believe that is fundamental to the success of a pro camera line from Canon or Nikon, (and previously Pentax and Minolta).
---Michael