[capableweb]

Developers of the core protocol would notice, add a flag and then miners/clients/exchanges who want to remain with the same dev team can signal they want to follow the "dev" chain instead of the "miner" chain.

Usually forks have checkpoints as well so things can't change willy-nilly.

[jstanley]

If blocks in the "miner" chain break the rules of the "dev" chain, then no flag is required. You'll automatically stick with the chain that contains valid blocks, as determined by the implementation that you're running.