My main question is:

What exactly means attribution for Wikipedia re-users?

Here are some options:

(i) WMF decides that new content can be accepted only if the author agrees that attribution means mentioning the Wikipedia.

(ii) WMF decides that new content can be accepted only if the author agrees to a main authors rule established and invented by the WMF (as I have shown it is a myth that the 5 main authors rule is the essential rule for the GNU FDL attribution)

(iii) Attribution means that a list of all contributor names (of a document, i.e. Wikipedia article) is necessary.

(i) Attribution means that a list of all contributor names and IP numbers is necessary. (Please note that an IP "represents" the author in WMF projects.)

Please consider:

Any change of the GNU FDL has to be similar in spirit. This means that the main principles in the preamble cannot be changed: "Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others."

I cannot see that a CC-BY-SA re-use with simply Wikipedia as attribution would fullfil this criterium.

Here are another questions:

* Will there be an opt-out (i.e. deletion) possibility for authors which doesn't want their content dual-licensed?

* Will WMF delete all content of users and ban them permanently for all WMF projects if they - don't share WMF's licensing interpretations - announce legal actions with the purpose to make a court test of the validity of the GNU FDL update and/or WMF's license interpretations?

Klaus Graf