That's a good theory, could also explain why pixel devices are only available in only a small part of the world population.

What other OSes are out there to choose from?

Of course they would. What I said was hypothetical but if it could have been done it would be a market disruptor.

3 years life span is questionable considering pixel 7 and 7 pro quality issues (falling buttons, cracking camera glass)

Fi user here: I don't see this offer anywhere. Inside the Fi store it shows a $1000 trade-in offer but that's it.

that seems like a fine tradeoff. I'm already on Fi, and the service is great, even internationally

Also true, but that's not what I meant: buyers not replacing the phone they have often enough is solved, battery decay and lack of updates. But there's not much that sets the $1000 replacement apart from the $300 replacement. A $1800 replacement? The market for a $1800 phone that is as obviously different from the rest as a foldable is many times bigger than the market for a $1800 phone that is just better somehow. My prediction is that unless some cheap newcomer brand shows up with a foldable, none of the established will ever make the first move and offer their foldable cheaper, no matter how low the actual cost might be.