And then people like me can pay another 899$ or whatever for an electronic viewfinder And I am sure EVFs will not be so expensive when they are mass marketed.
The most expensive add-on EVF from Olympus, Panasonic, Sony, etc., is the one for the RX1, which is $450. The top one for the NEX is $350 and for Olympus is under $300. Each of those companies has released entire camera bodies with built-in EVFs for under $1000, and some under $800. In general, on a camera already equipped with an LCD for live-view on the back, an EVF isn't much more than a second screen. As such, if you take a DSLR, remove the mirror-box and replace the OVF with an EVF, it should be less
expensive to produce. That's one reason why you'll see the OVFs replaced on the lower-level DSLRs first. Consumers at that level won't care (or even know) about the marginal benefits that an OVF has.
A system like this removes the third biggest hurtle for mirrorless migration. The top-two are marketing and a well-developed lens selection. If Canon brings this system to the EOS-M and Nikon refines their on-sensor PDAF, then eventually one or both will put the marketing $$'s behind it, and #1 will go away. #2 will simply go away with time. The high-end OVF-based bodies with be around for a long time, but the rest ...