Airlines can and do switch like aircraft at the last minute all the time. Do all the planning you like, but you won't know for sure until you're seated and look at the safety card.
So unless you intend to have a "Qantas never crashed" tantrum in the airport, you may be out of luck because the only airlines in the US that have not ordered the MAX are Spirit/Frontier (Greyhound with wings) and JetBlue, and they don't fly everywhere.