This seems odd, as the DFW flights have been some of the hardest ones to score F on for the 77W (LAX is hardest from what I can see) and the ones which seem to pack the J cabin the most even with 52 seats. Even if most everyone on DFW TATL F is using SWUs, that's still 60 biz seats which are mostly being sold at peak times. Going to the 772s would seem to represent a dramatic reduction in capacity for premium cabins.
I would frankly be stunned to see ORD switch to 77Ws over DFW. I'm not sure ORD would actually sell any more F seats on these planes than Dallas does. I could see MIA-LHR going to two 77Ws before those planes show up in ORD.