I think the whole project would benefit immensely from Open Sourcing it. Various license alternatives exist. Now I think it's just sorf of a piling amount of stress on just one man, who could let it go and just manage it and let others do the programming work.
At the moment, it's Toady's baby and Toady is welcome to release just as much changeability (e.g. the raws) as he wants. That's possible to also do via a limited Open Source way, but as it looks like the Source itself (as opposed to the working data) is what he wants to keep personal (give or take the occasional trusted co-developer, like Baughn, if I understand that situation correctly) then there's no need to make any changes.
What I might be tempted to do, though, if I were in the midst of something with as much public concern, would be to consider what I might want to happen "should something happen" (wood being knocked upon, as I write this) and get it at least quietly arranged so that this happens 'in the event'.
At it's simplest: designate trustees to be recipients of the source-code, with instructions that a specific person or group be given certain development rights, that a person of group be found by those trustees towards the same end or that the code should now be released (perhaps via a transitional coder) into the Public Domain, to name just three options of many more.
If non-PD, then the remit might be "get it debugged and officially released, but implement no more new features that aren't already earmarked". Whatever, whether the aim is to be a nice little earner or just to be Toady's intellectual legacy is up to Toady, personally. I'm sure I wouldn't fault him, whichever way it went.
Ok, so if Toady suddenly dropped off the world (for whatever reason, including just getting fed up of it) and stopped coding, and the various server subscriptions expired and the community was left with a half-finished and buggy version 0.45.13 floating around in Torrent feeds, it wouldn't be the first time that such a promising project came to an end, but obviously this particular project is of one that a lot of the people reading this have put a lot of personal time, emotional commitment and intellectual thought into, so I'm just thinking (perhaps selfishly) that there should be an official continuation. But, as I said, it's Toady who should (one way or another) have the last word.
As a kind of example, Terry Pratchett has more or less stated (I'm paraphrasing, and his attitude might have changed as well) that he really doesn't mind too much about Fan Fiction for the Discworld canon, but
he doesn't want to see it. This is a practical solution to the problem of not having to say (again!) "Yeah, I was looking forward to writing the book about <some situation>, but now I can't...". Because (frexample) enough people say that he stole the idea of his
Ponder Stibbons character from Rowling's Harry Potter (for which he would have needed a handy time-machine, of course), never mind the problems if he's thought (or intimated) to steal from a fan. Ditto with the cardinal crime of fans Speculating on public forums in his presence, for the same reason.
Now, I know there are people out there who have privately (or in semi-private places) made their own fan-fiction (including slash-fiction), and I've got a few of my own, in potentia, (not yet escaped from my head, but more or less fully-formed). As and when he dies (a sad occasion, and of course he has the much publicised illness hanging over him), the Discworld estate is naturally going to belong to his wife and/or daughter (with possible sidelines to Briggsy, The Cunning Artificer and various others), but it
may be that he (or his estate) will officially let fan-fiction flourish. Regardless, it
will happen (as it does already, though in a subdued manner by those who care about the aforementioned problems), but if a statement along the lines of "To all my fans, I bequeath the right to speculate freely, and write what you want that in Good Conscience keeps to the spirit of Discworld, so long as you don't charge anyone for the privilege of reading your creations" (and/or a variation on the current usual practice for performing his plays, that he doesn't mind amateur groups doing so, so long as they ask him/his agent for permission and make a token donation to the Orang-outang Fund).
Note that this is just an example. I've no idea if it's anything like what PTerry has set up (or what his estate executors will do, In The Event), but I felt I could go into more detail about something on this forum about a person that (to my knowledge) does not frequent this place, after going as close to the wire about this particular Creator as I care to do (and feeling uneasy enough about what I did say).