With the same old sensor and digic V (Not V+ note) I doubt the video will be any better than the 550D, and certainly not up to the 5DIII, let alone a hacked GH2 at probably less money.
Bummer I really don't want to be doing with smaller-than-C sensors.
I am waiting for 5D2 price to come down as well as waiting for this line specs. The T4i specs and performance will give me a glimpse of what will be of 70D/7D2.
I agree with you, even with a new sensor and Digic 5, the video quality will not be the same level as a hacked GH1/GH2.