That really sucks. I know he's had his health worries for a while now but doesn't make it suck any less.
I've been thinking a lot about DW's history lately, and one thing that has occurred to me is how rough calling his DW a 'Disney knock off' is. I'm sure I've even been guilty of making that point somewhere in the past. It's true that the influence is there to see, from building designs to the Paddle Steamer to the Matterhorn with a ride in it, to the animatronic animal show to so much else. It's there and it's not a secret. He wasn't alone in it; there are a lot Disney knock offs out there
The thing about John though, is he studied it understood why it worked, and took that understanding to make his own totally different and unique thing. Look at all those Disney knock offs that have sprung up in Asia (or even the entire Chinese amusement industry as a whole) and tell me the people behind them understand what makes a park good. John not only understood why Disney worked, but was able to craft it into something else entirely, an Australiana version, that was really charming and amazingly good. That's an effort, I don't think there's any one else that could have done it.
There are a million other things he did, but that will always be the one that made the most impact on my life, RIP mate, see if you can book a chat with Walt while you're up there.