Mike Godwin wrote:
... but I think as a practical matter this is not a problem, because you'd have to find a copyright-holding Wikipedian in Germany who (a) doesn't want to relicense, and (b) would prefer to spend money on litigation rather than simply withdraw his or her contributions (from Wikipedia, not from any other venue that is using the content consistent with older GFDL versions) . And even if you could find someone for whom both (a) and (b) are true, the fact that WMF would likely withdraw the contributions anyway if litigation were even hinted at would go a long way towards building a legal defense for WMF in such a case.
Mike, you may have noticed that this list includes some people who would treat the most improbable of circumstances as though they were everyday occurrences. :-)
Ec