This is huge. It means the Bitcoin and Ethereum communities can now confidently ship the opcodes and precompiled contracts to check ECDSA signatures on P-256 in addition to K-256 curves, and stop worrying about possible NSA backdoors based on the chosen seeds (quantum computers are another story).
I turned out to be right in my advocacy years ago, here is my post: https://ethereum-magicians.org/t/eip-7212-precompiled-for-se...
If there’s one thing everyone knows about conspiracy theorists, it’s that they’re willing to accept concrete disproof of their theories. /s
Nobody conversant with elliptic curve cryptography research believed there was a backdoor based on these seeds; for a number of reasons, best articulated by Koblitz and Menezes (who took on the question directly).
But it's nice to be able to shut the whole unproductive debate down directly.