I don't want to open a new thread because I have on my mind something related to this issue, while it is not connected directly to the present license migration. At the other side, it is a licensing question of the future.
Because some articles have thousands of editors, usually it is not reasonable to list them all in some random derivative work. Because of that the recommendation is to use a link.
But, we are not so far from the point when listing all links of previous works wouldn't be reasonable. Imagine that a lot of universities are contributing to the free knowledge corpus and that they are using each other's works. Imagine that a number of companies are interested in such knowledge sharing, too. We would easily get thousands of links for a single page.
So, the ultimate copyleft license will be PD-SA.
Other thoughts?