Originally Posted by
btonkid12345
This is irrelevant to this thread - the UG list and clearing into C+ - as basic economy fares do not get upgrades or get one on the upgrade list.
What happened to you was an OPUP - you were on the standby list for a seat, and when the GA got around to assigning you seats, all that was left was C+, so you lucked out. There are multiple reports of this on various threads. But, irrelevant to this thread.
Is it though? Perhaps if the C+ upgrade list was empty, but I've never seen a flight go out with an empty C+ upgrade list to/from ATL. It is not unlikely that the BE pax cleared directly into Y+ ahead of the medallions on the upgrade list. This directly ties to OP's question of how likely this option is to be successful for him/her.