Something I haven't really heard much of (but seems critical):

No blockchain is immutable... ever. Developers and miners can always change the rules. But, the rules can't be changed in SECRET. It must be public. It must be debated. It must be written. It must be reviewed. It must be adopted (by miners, and ultimately by users).

The advantage crypto has over the banking system is that our mistakes and corrections are public and transparent. Banks do their dirty work in the shadows.

EIP999 seems like a no-brainer and could serve as a model for an acceptable fix in the future.