I actually get a lot of value from cloud hosted solutions, I bounce between 2-3 machines daily and multiple OS installations several times a week, and would like for my notes taken on one machine to just be there when I write notes on another machine. Another thing I need to do often is type up design docs collaboratively, we use google docs for this currently but it sucks for our use cases. And finally, I read and w…
You can also have multiple vaults, and if you want to collaborate, you can share that vault with someone.
Realtime collaboration may be a bit dangerous with syncing over a cloud provider. They are also planning a subscription with note hosting - perhaps that will include some form of collaboration.
If you put all of your GH wiki pages into a single vault, that may be a solution (though I don't think it's possible to create a solution to your setup in the most general setting - you'd have to be able to link to any file on your OS).
But you can throw your data up on a server and make it accessible from anywhere with an internet connection