From the above link:
"The new installment of a decades-favorite franchise premiered at the end of Sept. on CBS Television Network’s digital subscription streaming service, breaking their single-day record for new subscriber sign-ups. ."
I have seen other wrote-ups that have lauded the success - viewership-wise and monetarily - of the show.
It won't "migrate to on air TV", because its purpose is to drive people to All Access. Moving it to regular TV would defeat that purpose. I think CBS believes streaming services are the future (and I agree with them), and they want to be out front. From the very start, this show was never intended for anything but CBSAA, and will remain there, no matter how successful it becomes.