VampirLestat: Would I have to download all of them all to be able to keep them?
And would we get notice on time, so we can do that?
First question: yes, but you'd have to do
more too. If your downloaded copies are your only copies, and GOG is down, then they are not even a backup. They have now become your primary source (this is bad to have a primary source only and no backup).
The only way to definitely "keep them" is to have
multiple backups of them, with some stored at different locations or in the Cloud (i.e., in case your home catches on fire or something).
In other words, don't think that downloading one copy of your games means that they are safe. That would not be true. Any hardware has the potential to fail at any time. Or it can be stolen too. So having only one copy is the opposite of safe.
As for would you get notice on time: nobody knows. GOG says they would provide that, but that's a
non-binding promise and therefore it amounts to nothing more than meaningless fluff words. So best to presume, no, you wouldn't get enough notice, if any.
sanscript: 2. Was this hyped up, exaggerated fearmongering?
No, I don't think it was. Is it not a fact that GOG has been consistently losing money over the past few quarters? Unless that is untrue, then planning for GOG's demise is not fear-mongering; it's just being wise and protecting one's investments.