The most honest answer is: we don't know if Apple will still service them then, because they've never made a product like this for comparison. We also don't know whether non-Apple service centers will be able to service them later, which might even be a more important question. (Once your device is out of warranty and AppleCare coverage, Apple's repairs are going to be pretty pricey even if they're still available.) But I don't think saying "well, they only support phones and computers for a few years after they stop making them" is necessarily a guidepost here.

> Also, why not make it so they can be used passively? What's the downside?

My quasi-educated guess is part marketing, and part technology. The marketing part: Apple considers these AirPods Pros that cover your ears, and insist that they have all the AirPods Pro features. The technology part: from what I can tell, these headphones are DSP-ed up the wazoo, more like HomePods than AirPods, so there's a good chance that passive mode will sound like crap.

I know a practical counter-argument is "so what, there are other active noise-cancelling headphones that let you switch them to passive mood and they sound like crap when you do that and everybody's just okay with it," but, that is not Apple.

(For the record, the AirPods Max are not on my shopping list.)