User blog comment:Rupert Giles/Global Navigation Update/@comment-23895839-20141204211157/@comment-452-20141205142530

I agree that is it "unclear" what will happen, but it will not change to the old one.

http://community.wikia.com/wiki/User_blog_comment:Rupert_Giles/Global_Navigation_Update/@comment-BertH-20141204194147?permalink=765824#comm-765824
 * Further changes to the new design may happen, but we will not be returning to the old design.

So, apparently they won't just be "turning it off" at the end of the test.

This means that one of four things will happen at the end of the test:
 * 1) Nothing will change
 * 2) Everywhere will change to the CC version
 * 3) Everywhere will change to the one of the three test versions
 * 4) Everywhere will change to an updated version

The last one is the optimal outcome, and they'll actually change the header in line with feedback - but knowing the glacial pace at which updates are usually made, this seems unlikely.

It seems likely that #3 will occur - whichever way resulted in the most edits/ad-views will be used. (This depending on what they're actually measuring.)

If any further changes happen due to feedback, we probably won't see them until at least February.