I am very disappointed that GRIT TV was removed. This was one of my favorite channels. It was replaced with junk as far as I am concerned. I hope it will be reinstated in the near future.
GritTV, MeTV, CoziTV, Decades, Dazl, and many similar are broadcast networks carried by a local TV station. If that station decides to change to another network, there is nothing Comcast can do. Comcast just passes on what is aired.
If you see mention of call letters during commercial breaks or as an on-screen 'bug', then it is a local TV station carrying it.