>The neat thing about bitcoin is that the incentive to break it is so high that it would almost certainly be the first place you would learn that SHA2 had been broken.

We actually see the incentive in the other direction, if we were able to reduce the search space for bitcoin proof-of-work (by applying thousands of higher-order algabraic theorems end-to-end to reduce the search space somewhat[1]), we would be financially incentivized not to tell anyone and mine at a discount. The financial incentive is against open research and disclosure. We don't get anything out of disclosing this except a neat publication.

[1] interestingly, ASICs (which are usually used to mine bitcoin) basically encode every operation verbatim, they don't use higher order mathematics at all. However, reducing mining complexity is not really on the horizon, even with our latest approaches, since it would require end-to-end complete control over the double-SHA-256 pipeline. That's considerably harder than just finding a collision when you're allowed to search just the tail part (the final rounds).