I thought they were just done testing - I downloaded the new (current beta) version from the app store and I'm running that now. I couldn't figure out how to access the app any other way.
My other thought is they decided my feedback was not worth much. 
Starting yesterday, when I try to open my chess.com app on my iPad I get the following message:
"Chess" Beta Has Expired
OK
My only option is to press "OK". I can't open the app.
I am a member of Beta. FWIW, the app on my phone works fine.