[int_19h]

Correct me if I'm wrong, but isn't a fork _always_ possible in a decentralized blockchain? And if so, wasn't the "the contract is whatever 50%+1 of the network decides it is" always part of the contract?

Basically, anyone can introduce the fork with any arbitrary changes (including reverting any transactions, or, for that matter, creating more money out of thin air) at any point. But the fork is only viable if the majority of the network decides that they want it. So the governance model was always "majority decides"; it was just made explicit here.

Furthermore, it's impossible to address that problem by any kind of governance, because - this not being a government - submitting to the authority of the governing body is voluntary, and the way you avoid doing so is... by forking. So a fork is always an option, simply by virtue of decentralized implementation.