It is almost the same thing that happened when SLRs appeared in the market.. Leica still produces RFs now and is earning big bucks from these cameras.. What is in the long run? 50% EVIL cameras comprising of PnS users and etc would be quite possible.
I see some parallels between what Pana/Oly are doing with the mirrorless with what Nintendo did with the Wii.
They were able to open up a whole new market for the more "casual" shooter, just like what the Wii did with the "casual" gamer.
(Not saying that mirrorless shooters are not "pro")
It did hurt MS/Sony but both were able to respond with their own motion-sensing hardware (Kinect/Move).
Canikon can respond just the same.