I think we have to assume that Cyan have lost commercial interest in Myst Uru. They couldn't see a return on their time but also didn't want anybody free loading on the back of it. That's a reasonable attitude.
But it's a bit like a patent if you come up with an invention you have a fixed amount of time to develop it and if you keep developing it the patent moves on.
Let it sit and it will lapse. Software is a strange case because it's copyright not patent.
There's also a little of the genie in the bottle once the open source is out there it is going to be difficult to control given the tools they are unwrapping then fair enough they will have the advantage of being able to produce cleaner code quicker.
I would like to see a list of the products they need to unwrap there's always a chance that some of them will have lapsed, or at least been superseded by newer versions with some of the older ones dropping into the amateur price range.
I have started looking at Alcugs and Almlys's new venture 7d7 I have come up with a game plan and an outline to see if it can support an Uru style non Myst universe avatar non violent game.
The first step is making an easier install of Alcugs or at least a smoother set of instructions to that end I am picking the brains of diefero who I might add is being surprisingly patient with me. I am working on the principle that stuff would be modelled using blender and the story like Uru a reserved cannon with fuzzy edges.
The outline is on the 7d7 site and open to discussion. I am open to suggestions provided it stays inside a family friendly rating. I want a story to compete with Cyan at present the alcugs Uru boundary is dubious but f we use alcugs for testing and then distribute on the new engine It should give us sufficient separation.
Ideas like this age Corsus may be able to exist in both worlds who knows someone might migrate taking a linking book.
If anyone wants in it's open house however expect trolls and spammers to be evicted. Honest debate will be entertained.