I hope they do release the source code under a permissive license... If not, this is a classic example of something valuable that will be completely lost to time. A nice sandcastle built below the high tide mark, if you will.
I am really sad to see this go. Though I didn't actually use it for more than a few hobby projects, it always struck me as very cool to be able to link things.
Thanks for working on this.
If you consider open-sourcing this it might be a project that gets support as there's nothing in the Google suite or others that comes close to this.