Happens in ATL all the time. Had a two day trip out of ATL once that began with a deadhead (on the last DAL FLT to ORD) the night before and we were the first FLT out in the morning. The plane was oversold and we didn't have "seat assignments" so they wouldn't bump rev for us. I told them that if they could find 3 PAX willing to get off I'll ride the JUMP and let the other 3 crewmembers sit in the back. She refused and told me it wasn't her problem. I then enlightened her that if we didn't make it to ORD then 76 of DAL passengers/rev won't make it back in the morning..................she then said it wasn't her problem and basically told me to scram. We called crew support, they called the gate and we all ended up going home with full pay for the 2 day. I don't know if the passengers ever made it down the next morning, but since ORD is a large base for SKW (UAX) and Jerry wants their F4D they probably called out a few reserves. Hey I didn't care.................I ended up with two paid days off.

They (ATL Gate Agents) have told me several times that if we don't have an actual seat assignment (even though we are must rides) then we are no better than high priority nonrev's and any rev misconnects will/can bump us.