What I think we've seen over the last 5(ish?) years is that it's not necessarily "stream or die". It was thought that cord-cutting would kill live TV. It didn't. Streaming services have cropped up that offer the same product as traditional linear cable/satellite TV with an alternative delivery method. So if you want live TV, you can pick cable/satellite. Or you can pick Hulu Live TV, YouTube TV, Sling, etc. They're all "streaming" but they're live TV.
I didn't articulate my point very well. What I mean is, judging by the admittedly limited sample size of young adults I know, they aren't doing ANY form of TV, traditional or streaming. They aren't using YouTube TV, Hulu, etc., any more than they're using cable/satellite. They don't care about the content that's carried there. They use Netflix, Prime Video, HBOMax, etc.
Of course, as I think through it more, I see another flaw in my thinking. What the above really means is that younger consumers are not watching sports anywhere, so my a la carte idea is perilous to ESPN anyway, because the example I'm giving as what ESPN may need to adjust to is a no-win situation.
I'm sure there are many young people coming up who still want to watch live sports. But I'll tell ya, in my sphere, though I've never thought about it, the youngsters aren't into sports like we were growing up. Pretty much everyone I knew--and know, my age--is at least somewhat interested in watching sports, particularly football. But as the age drops, that doesn't hold. I wonder how representative my experience is of the overall population.
Re: the rest of your post, I see your point and you've made a good case for why a la carte isn't a good idea for ESPN. But what's the solution, then? Whether they have incentives to keep doing what they're doing or not, they're evidently losing money doing what they're doing now, and that can't go on forever. You have to provide 24/7 content if you're carried by the cable outfits, and as noted, nobody is watching the stuff that's not live games. If not a la carte, then what? Only the US gub'ment can lose money indefinitely, a corp. like ESPN will eventually have to adapt or die.