No upgrade list is going to be absolutely accurate until 30 minutes before departure, when check-in is closed and upgrades are doled out.

You can pretty well tell when it is totally hopeless (#35 on list with 2 seats). However, I have been pleasantly surprised twice this year. Once from LAX-ATL, I was #8 for 4 seats when I checked right before leaving for the airport. I grabbed lunch and went to the gate only to find that I was #4 for 5 seats (must have been a massive SDC on/off that flight!). The other was SNA-ATL, where I was #4 for 2 seats. When I got to the airport, there had been an EQP to a plane with 4 more F seats. I still went down on the list, but ended up #6 for 6 open seats. I'll take 'em. The moral of the story is to keep checking - and anything can happen.