What are all the researchers in universities doing ? Couldn't they improve these models (they do have big brains after all) with tax payer's money and put the results under some cool open source license...
What if crypto is switching from mindless hashing as proof-of-work to training AI models as proof-of-work? That would mean suddenly big computing resources are available.
Maybe it's possible to implement it in a decentralized way with not-completely-useless performance, but by then OpenAI and others will be even more ahead. (Sure, it'd be good to have such an implementation, so maybe enthusiasts will do it eventually, but that's mostly for fun.)
Flip the timeline and crypto from the start would have had this as a goal.
1) The work has to be very hard to do (and quantifiably so), but very easy to verify.
2) The block's transactions have to be an input to the computation, and it has to be impossible to get the same output with a modified set of transactions.
Cryptographic hash functions fulfill both of these requirements. Almost nothing else does.
However, if blockchains switch to proof-of-stake, then the GPUs previously dedicated to that blockchain are available for other purposes. But the biggest GPU-based blockchain already did that, and Bitcoin uses specialized hardware that can't do anything other than Bitcoin's hash function.