Too big to fail? What would a bitcoin reorg mean?

Too big to fail? @cz_binance mentioned a Bitcoin blockchain reorg yesterday, in response to a suggestion made by @JeremyRubin. It caused uproar in the crypto community, and he's since taken the suggestion back. @Zaphoid and I chat live about what "Too big to fail" would mean for bitcoin, it's origins in the financial crisis of '08, and the Ethereum DAO bailout.