I have to wonder if Gray ever saw it coming, that one of these days WANF might be an independent. AFAIK Gray doesn't have any stand-alone (i.e., not co-owned with a major in-market network affiliate) independents. The closest thing would be WPGA in Macon (MeTV), and that poor little station has bounced all over the place ever since it began.
I can't imagine the suits at Gray are the least bit happy about this. If it were a case of a very strong legacy station going independent (such as WHDH, WJXT, or KRON), that would be one thing, but I'm not sure WANF has ever had anywhere near those stations' chops.
I'm pretty sure it was Gray that made the move. CBS was making a lot of money in fees from WANF to be an affiliate, and didn't have to do much work to get it. Aside from a dream of setting up a streaming OTT service in the largest market in the southeast, CBS probably had little motivation to take the affiliation from WANF and turn WUPA into an O&O. Especially at a time when their parent company is planning a merger, and their news department is in absolute chaos. Not to mention having to build a local news department from nothing in two months in a very competitive market. I don't think CBS wanted to make this move at this time.
Meanwhile, Gray, which has recently been building up a competitive news operation at WANF, has been paying millions of dollars for a CBS affiliation that apparently hasn't been paying off to their expectations. The network news department is a mess, and they no longer have rights to SEC sports. Without CBS, they save on paying for the network, and they can go after more lucrative local sports rights, which may become more abundant in the Atlanta market. They also can expand local programming, including news, where they collect 100% of the advertising money. They have some flexibility here.
The new CBS Atlanta operation is going to be a huge money pit for a long time, at the worst time possible. Sure, they can put on a happy face and spin it, especially when it comes to the new streaming news channel and a deeper presence in the South. But I highly doubt this was their intent.
I've been reading lots of ridiculous speculation and conspiracy theories on other boards about what this means for Seattle and Tampa Bay, where Paramount/CBS owns independent stations, but affiliate the network with other broadcasters. I really can't see Paramount/CBS wanting to take affiliations away from Tegna or Cox to create their own startup O&O operations on much weaker stations, when they could just merely sit back and collect the reverse comp money from the current, well-established affiliates.