Why would that worry you? Book the Western and if Hawaii does show up you can change your reservation. Best to lock in the 2012 rate now.For 2012 we are thinking about booking a Western Caribbean cruise but we are worried that a Hawaii cruise will come out for 2012. Do you think it is possible that Hawaii will come out then?
In my opinion LA to Vancouver does not seem likely because it is a day or two out of the way. I like to think that DCL is sending a ship to Asia, South america, or (less likely) Australia. I really think that Asia is a possibility. we can only hope!
ETA: Tokyo Disneyland will be almost 30 years old in 2012 as well. Remember that the first time the magic went to LA was Disneyland's 50th birthday and the first time the Magic went to Europe was Disneyland Paris's 15th. So we shall see.