Moxie's post looks solid, but there is a counter example: bitcoin nodes. They are a very loose federation of nodes that go through regular upgrades in the protocol. So it is possible.
But yes, it's also very hard. The bitcoin protocol didn't start out that way. It took a lot of knocks and bruises to get to the point they could upgrade all the servers in the federation.
Interestingly, the method bitcoin came up with allows protocol changes to fail, meaning the bulk of the federation never takes them up. Everyone gets a vote, and it only succeeds if the bulk of the federation upgrades. Perhaps from Moxie's point of view that's unacceptable, as it means he is no longer the dictator of the protocol.
Nonetheless, it is possible to design a protocol so it can be upgraded relatively quickly. Even if you don't do add "quick transition" features to a protocol transitions can still haven. IPv6 will replace IPv4. But as Moxie says, it's painfully slow.
But yes, it's also very hard. The bitcoin protocol didn't start out that way. It took a lot of knocks and bruises to get to the point they could upgrade all the servers in the federation.
Interestingly, the method bitcoin came up with allows protocol changes to fail, meaning the bulk of the federation never takes them up. Everyone gets a vote, and it only succeeds if the bulk of the federation upgrades. Perhaps from Moxie's point of view that's unacceptable, as it means he is no longer the dictator of the protocol.
Nonetheless, it is possible to design a protocol so it can be upgraded relatively quickly. Even if you don't do add "quick transition" features to a protocol transitions can still haven. IPv6 will replace IPv4. But as Moxie says, it's painfully slow.