I told you already: "preparing" sounds too much like a euphemism for "fucking around"
Quit the bandying of hashing algorithms around already, we need to pre-empt their attack, not sit around waiting for it to happen. If the lead-time to develop a Keccak ASIC is long enough, we need to get the ball rolling, as soon as is diligently possible.
Simply changing the PoW pre-emtively sets a bad precedent because it harms good miners and long term investors and it will harm cryptocurrency in general by showing how flippant the community can be. Most of the users and core developers I have spoken to do not support pre-emptively changing the PoW algo, thus this HF would have very few following it , and we would not have the moral high ground.
Perhaps there can be another way though to prepare .... where we develop a full node wallet , like Knots, where it simultaneously mines the other PoW algo on a testnet, where during times of contention users can enable this secondary mining and have the users ready to quickly HF over when ready.
True, someone aleready experimented a multi algo coin, i forgot the name of the coin, but it can't bring good results as each algorithm requires custom GPU tweaks, so if you change the algo at each new block, miners will leave. Annother sollution would be to define an ASIC safe algo and use it, i don't know much about Keccac, but if luke-jr believes that he can be amended to fit in bitcoin-core code, then we should go for this sollution.