Marc Laukien responded to some emails regarding the reasons for the end of Wish and what may happen to the code over on Stratics:
Wish has been shut down because with the data we gathered during the first 10 days of our Beta 2.0 test, even with our best-case projections for player numbers, we could not have reached enough subscribers for Wish to sustain itself.
This is the reason that I already gave to several fan site managers, and it is the only reason. There have been no technical problems out of the ordinary, we have not been bought out, and neither is there any truth in any of the other rumors that are being spread in the Internet.
This reason is hard to accept for some fans of Wish, and I can understand that. There has been a very loyal and dedicated community around Wish. But it is simply not large enough to support a group of over 32 full-time game developers, plus many others that worked as consultants.
And later:
It is very unlikely that the Wish source code will be released under some form of open source license. The code depends on several commercial products, so you couldn’t just use the code as it is. Furthermore, you would need a large and highly experienced development staff to actually use the code, plus a lot of support from the original authors, something that most likely would not be possible. I’m really sorry that I cannot give you any better news, but knowing the complexity and required efforts of development, I’m afraid that Wish as a community project is not feasible.
So there you have it. They did not think the number of potential subscribers would keep the game afloat. The code is tied up in a bunch of 3rd party rights. The end?