To me, this Sony camera looks like it's set to compete with the very over-priced C-300.
I believe the Sony will probably be at least 4:2:2 8 bit and if it is, it will completely destroy the C-300, especially since it's reported to be able to shoot really high frame rates of 480 fps and even 960 fps at reduced resolution (but we will see about that).
I'm sure as we speak, many people are cancelling their C-300 which is in back order right now.
Canon's pricing has been ridiculous lately (the C-300 is so high it's laughable) and the 5D3 is priced a good bit more than the D-800,even though it's under-spec'd
Sony video is going to give Canon a huge reality check at NAB, and I am glad. This will force Canon to start acting like a reasonable company and COMPETE, something they haven't had to do for a long time. Especially now that Sony can adapt all EOS lenses perfectly with the Metabones adaptor.
The EOS 4K will be a bit unique in that it's going to be full-frame video. But Canon has been a bit up-staged at this point, so they will be forced to include features in the EOS 4K that they otherwise probably wouldn't have.
As for the C-300, it's going to be obsolete very quickly so Canon should just move on from that camera. It was close to being obsolete the moment they released it, especially since the Sony F3 can already do 4:4:4.
For me, I want a Full Frame video camera that can do crop modes of 1.6x and 3x (like the Nikons), a flip screen, true HD, peaking and maybe a few other bells and whistles. A better 5D3.
But now that Sony is going to be shooting really high FPS rates, I'm thinking the 4K EOS will have to be able to at least do 120 FPS.
The moral of the story is: Competition is GREAT for everyone.