Is that the sort of longevity one can expect from any winter tires, regardless of brand and quality?
There are a lot of "it depends" here. It depends on far you drive and how particular you are. Other "it depends" are how many months you run them, what the temperature is, and how good are the roads you drive on (The gravel on the roads that the DOH puts down really chews up snow tires).
Some winter tires aren't good even when new, and some are really cold weather dry/wet pavement tires (The Pirelli tires Tesla sells appear to be in this category). If the tires you choose are designed with either Europe or Japan in mind they will have "snow tire wear bars" in addition to the regular wear bars. In countries that require them, they aren't legal snow tires when those wear bars are showing. Even if you purchase tires without those kind of wear bars, you should act as if they were there.
When I lived in Vancouver, I always put on either four of the best winter tires I could find, or what would today be called severe service all-seasons (an example is Nokian WR-g2). In the Pacific Northwest, the snow is very slippery because it typically falls at right around freezing--sometimes there is a layer of ice under the snow. In the Midwest (NE, KS, ND, SD, etc.) the snow is dry and packed (usually) and you can get away with a lot more (most of the time, anyway).