As long as the devs and exchanges agree on a fork and change the ticker of the current XMR into something else, hashrate doesn't really matter.
Then you will have a new altcoin like ethereum classic, and the old monero will still live on. The only way to do this properly is to hardfork the chain, and force the wallet upgrades.
What if the old monero becomes monero classic? It's devs and exchanges who determine the name, not miners unfortunately