I think it would be nice to archive off the older SQL version forums so the threads are still available even if the posting ability is not.
I do like the idea of having a T-SQL forum and a Database Administration forum that aren't version specific, but have a radio button forcing people to choose which version they are posting about which will show up as the first few words of the subject. That way people who ignore the "post your version" stuff, have no choice but to list which version they're talking about.
All threads will be available, just closed so no new posts. Both to consolidate, and also to limit spammers that look for old threads