- Later this month, we will post a re-licensing proposal for all
Wikimedia wikis which are currently licensed under the GFDL. It will be collaboratively developed on meta.wiki and I will announce it here. This re-licensing proposal will include a simplified dual-licensing proposition, under which content will continue to be indefinitely available under GFDL, except for articles which include CC-BY-SA-only additions from external sources. (The terms of service, under this proposal, will be modified to require dual-licensing permission for any new changes.)
What's the plan for making a final decision? There will probably be too many people involved to ever achieve anything close to a consensus. Are you planning a referendum?
It will be the obligation of re-users to validate whether an article includes CC-BY-SA-only changes -- dual licensing should not be a burden on editors. This is also not intended to be bidirectional, i.e., merging in GFDL-only text will not be possible.
How will that work? If the terms of service have been modified, how does one upload CC-BY-SA only content without agreeing to those terms of service? There needs to be some way for re-users to know what license things are under, you can't just leave it to them since it's impossible for them to find out if it doesn't say anywhere.