they could also switch to POS and became the hero of the "green" for having saved the world from the "Bitcoin environmental disaster".
There are so many incentives to do so that I can't believe they won't.
Discussion
So in this case you would just have created a dork that they can't even control since they at best can get 2-3 million bitcoin assuming most of the hardcore bitcoiners aren't gonna be selling for an etf. They would now have a bitcoin they could be prevented from using by major bitcoin whales or more likely they would change issuance and a system they can control but now not gonna be useful as a money. Who's gonna adopt that again?