I know this is a very prickly issue, and I'm going to get a lot flak for saying this, but...I think it's time we reconsidered the ramifications of the GFDL. I'm not interested in rehashing what's been said before in favour and against using the GFDL, but last night I thought of a solution that seems it'd please everyone; basically we do not ask old users to relicense; they can do so voluntarily, but there will be no community drive to get established contributors to multi-license or relicense their contributions.
Instead, we make all edits by anons and new users after a certain date dual-licensed under the GFDL and the CC-by-sa (or some other preferable) license. Sure, this does not solve anything in the short run. However, the point is, eventually, some time far far away in the future, everything on Wikipedia can be assurably be useable under both the CC-by-sa and GFDL licenses. Whether we want to then switch solely to the CC-by-sa or stick with the dual-license is not a decision for now.
However, I think this is probably one of the very few ways to switch licenses if we ever need to. Turning the giant oil tanker of licensing contributions around is very difficult, and will take years, but such is the price of progress. This way, everyone is happy; if people want to change Wikipedia's license (or at the very least make it dual-licensed so as to avoid all those annoying problems with using GFDL material), they can do so gradually, and the GFDL will still be preserved.
If we want to change licenses, I think this is a decision that should be made sooner than later. I am not suggesting rushing the decision, but the sooner we do this, the faster we can turn the boat around. Of course, if the community wants to simply stick with the GFDL, that's okay, but at least this seems like a reasonable "exit route" if we ever need it.
John Lee ([[en:User:Johnleemk]])