I think your assessment is fair!
It sounds all over the place, which is usually how my mind processes go, except for the one thing about the point about not using the dual pixel AF. I don't shoot much video today, short clips here and there. I take time and am thoughtful about my still photography. However, when I want to capture video... I just want a little less thought a little more auto (at least right now), and I think the 70d may give me that, and incentivize me to increase my repertoire.
The 5d3 may expect to much of as a videographer. It's beyond my skills as a photographer in that it's capable of much more than me, but at least there I am comfortable with all the control I have after 15 years of using slr's.
So _in my mind_ I may be more likely to pick up the 70d and actually go out and get better at shooting video, maybe even to the point where I get more comfortable with it, learning all the nuances and being able to think more about the shot, than simply what I want in focus and trying to keep in it focus myself. Lowering the barriers to entry....
Or maybe it's just my GAS creeping up again! ARGH!