The policy did fail because Hitler was going to go to war no matter what but that is only with 20/20 hindsight.
Appeasement wasn't the right policy, it was literally the only policy available to the UK at the time.
I agree that we need to take a hard line with China though, I can't see how this is going to end given their massive increase in military size and technology plus we are all so tied together financially that we could cripple each other long before a shot is fired.
My friends seem to think that war is the only way this will end and I've got a young son so I sincerely hope not.
I just watched two history professors debate this very topic here: https://www.youtube.com/watch?v=fmyecSXOla8
A very interesting watch because unlike hit and run downvoters, I am interested in learning.
side note: I now don't know what I think - both arguments were very good.
And it's plausible that anything short of Churchillian intransigence would have lost that war. Even a "smarter" craftiness could have failed.