I'm wondering what kind of technological change would be large enough to force the popping of this bubble, as opposed to the likely economic or other triggers?

Would another order of magnitude decrease in the amount of compute for a model do it?

Would the cost of compute falling by an order of magnitude in a black swan event?

Or, perhaps Jevan's paradox[1] kicks in, and we just eat up the extra capacity in new uses.

[1] https://en.wikipedia.org/wiki/Jevons_paradox