There is the Founders Copyright project that tried to adjust the copyright expiration time span to a much shorter time.
Is there something similar in software? As far as I understand, a project can release the source code and assets under a permissive license when the interest to the project starts fading so that the community can pick it up without problems, and it is not uncommon to do so. However, are there cases when this release is pre-announced initially and is a part of the license?
There is a similar question: Is there a temporary copyleft license?
The difference is that I want to know about projects where something like this was actually applied ("shorter copyright time span"), not how to do it in general.