I think things are going to have to sort themselves out. As mentioned earlier, it will often be hard for the agent to handle everything and moving people to c+ is probably not going to be their primary concern. Also mentioned is the fact that a lot of upgrades now happen at the last minute and that makes thing difficult.

I think on occasion you might be able to ask to be moved into c+ if a seat opens up. I usually travel with my wife and since we want to sit together that becomes problematic. We have turned down the last FC seat and would turn down the last c+ seat if that even becomes an option.

Right now most people aren't aware of this change. On MCO-ATL and ATL-LIT today there was no announcement and the seat covers had not been changed. They didn't say drinks were free, but I asked on the first flight and didn't even ask on the second (getting free drinks on both). More significant to this discussion is the fact that I saw at least five empty seats in c+ on the ATL-LIT flight. I think there had been 4 empty FC seats this morning so this might be due to last minute upgrades. I didn't even look on the MCO-ATL flight because it's so unusual to see any empty seats most of the time.