If some miners amend their software to ignore blocks that have an OP_RETURN > 80 bytes, then they will create soft fork. Their chain will be shorter, it won't recognised by exchanges or wallets at first, but that chain will be more resistant to legal attacks. I accept that legal attacks can still happen for other data exists on the blockchain. But as Nick Szabo recently pointed out, the threshold of proof is much lower when content is held in one place one OP_RETURN. The content is easily accessible and viewable with tools that everyone has on their computer. A new mining network would be small at first, but that version of Bitcoin is more resistant to attacks, then it has the potential of becoming the main chain over time. How things pan out in the future is dependent on how governments around the world react. But we have precendent with Bitcoin SV where the EU prosecuted node runners for content that was in the enlarged OP_RETURN. If there is any chance the we can save Bitcoin from this malicious attack, then it at least deserves some consideration.