(Basic) question on upgrade list
 

I am flying tonight (in about 9 hours), I checked in and the upgrade list currently shows me as #3 out of 11 on the list.

It also says that seat availability is 6 in First and 12 in Coach.

Do I read this correctly: unless more than 3 people with higher priority check in between now and tonight, I will get upgraded?

Does this mean I won't be cleared until I am at the gate or is it still possible I will be cleared before heading to the airport?

Or they sell the seats outright. And yes, you will be a battlefield upgrade (at the gate).

Not totally. There are many other things that could happen to take those F seats away. Some examples:
- People buy last minute F tickets.
- People SDC from other flights onto yours who have higher priority (though this would eventually show up on the upgrade list).
- People take VDBs from other flights and are rebooked into F on your flight out of courtesy.
- IRROPS results in others being rebooked onto your flight (F or higher priority elites).