Threatened or vulnerable listings are fundamentally a future-oriented status. They say, based on x, z, and z trend (these almost always include habitat loss/fragmentation or over-consumption by people...
see Chinese Paddlefish in the news today), we believe this species is likely to face endangerment in the future. So, sure, I hope the Polar Bear's future is bright but until any of the wildlife agencies responsible for such things change it's status in a positive way, then I'm not personally optimistic.
My original point was to say that if your documentary said the polar bear was listed as endangered then I agree, it was inaccurate. It wouldn't necessarily surprise me if they were using the term generally and not status-specifically, which is common but misleading. I also thought your point about polar bear numbers moving from 10K to 30K from the 1960s to today, while correct, suggested that was the species' entire story, which of course it is not. You're obviously a wildlife lover so you know threats to animals are like a whack-a-mole game, just because we successfully solve one (over-hunting) doesn't mean another won't pop up (habitat loss or human encroachment).
And, of course, there's all sorts of things that could happen to the polar bear species.
I've seen a few reports that they're adapting in different ways, heading south, beginning to mate with grizzlies more to produce the Pizzly Bear...nothing scientific, just the odd story. Who knows.