If CBS did not have the stomach to launch a news operation in Detroit in the mid 1990's (when Detroit was DMA #8) why would they do so now with a rapidly sinking and even less important Detroit market today (at DMA #11 and likely to drop further as the population continues to move south)? But then again stranger things have happened. I personally think they could perhaps set-up a bare-bones news operation - perhaps a 15-20 minute newscast - something like that.
The Detroit market loses revenue by dropping from the top ten market category as many new product introduction media spending programs focus on "top ten markets. Also just today I was reading where the Atlanta metro just knocked out Detroit metro from top ten metro area population ranking (although these are census defined areas not DMA's).
I don't disagree with this. However, notwithstanding the economy, there is, like you said, potential for setting up a bare-bones news operation. A behind the scenes writer or intern can write the local content, and then out-of-market anchors in another market can record it in advance.
What I have been seeing happening in smaller markets is that some less successful network stations have been cutting out their local news departments and farming out news responsibilities to their competitors. While you don't see this trend in the bigger markets, it could eventually happen.
We also have what's called news exchange partnerships...TV exchanges with radio and print, and radio with print and TV. However, this trend has been slow to develop because a lot of broadcasters don't want their listeners to know they have to "share" with other sources to get information. That trend needs to change.