Did StackOverflow actually comment on when the switch would occur? I am sure they will post about it but I see a bunch of large companies saying "we will switch". I don't see a lot of companies saying "we have switched".
I want to see them apply logic and reason otherwise it might be difficult for me to continue to view them as a credible source of technical information. It will be interesting to see what choice they make.
Proof or it didn't happen.