What happens when Scragg finally just has enough, what happens when Rooks (thanks for being a trooper) decides it's not worth the effort anymore?
Most likely someone makes a new one. Even if they don't share any source, a good amount of people already know how to pull data from the game's AH servers and there are alternative projects with similar layout(Atom0s made a private server site with similar functionality at some point).
The bigger loss is the community, and at that point sharing source isn't enough. They'd have to be willing to hand off their domain, backend data, etc. I'm sure if a time comes when they want to get rid of it, that'll be considered.
My concern with fan passion projects like this (non open source)
I get the value of open source, really. However, there are security concerns to it, especially with something as old as ffxiah. I don't think it's always in the best interest to open source things; though ideally there would be a backup or contingency plan in place in case Scragg has to abruptly disappear.