Yahoo may close down Groups anyway. They haven't been maintaining or fixing or anything in their regard for some time.
Personally, I would like to see everyone rescue their archives and delete their old Yahoo groups, so that Yahoo would get the message that they failed with their shiny new NEO design.The more "empty" unused groups that sit over there, just serve to be something they can "claim" exists, to their advertisers. When in reality, they are not active or generating content for ads whatsoever.
But I also know you can't legally just put the archives of a Yahoo Group somewhere else online. So it's akin to starting over. Still, having the archives even in a zip file and sending it to any members that would want it would be a start.
Having been in this fight since August 31, 2013, and struggling to get the world to see what Yahoo has done to disabled, elderly and the rest of us, I'm ready to start the exodus. As soon as groups.io can serve as the place to go, I encourage everyone to start over here.
I still however, encourage people to archive their data. Even someone like Mark, who is kind and caring and understands the value of archives, can NOT promise that something might not happen to destroy the content. So I implore everyone to safely archive their data, whether starting over or staying put. It's the smart thing to do where the Internet is concerned.