Gydion: Huh? The games haven't been available to purchase for the past five months.
Jonesy89: Yes, but purchasers till have access to the copy they purchased; probably a good idea to back those up onto physical media in case GOG has to take even the purchaser copies as well.
It's always good to have backups, in case something happens with the files, we never know, and better safe than sorry, but since GOG treats their digital titles as if they were physical copies, I don't think they'll remove access to the files from those who -- legally -- bought them. A few games have been removed from GOG's catalog, and they're still available to those who purchased them, the only reason I can think of a backup is if something happens to GOG itself (which can happen, obviously, albeit in a hopefully distant future).
For now, the classic Fallouts will remain in our accounts, and I don't think ZeniMax/Bethesda has the legal rights to ask GOG to remove the games entirely, they were sold during an agreement with a previous publisher, and the customers who bought them have nothing to do with whatever rights were sold or lost or whatever, so they should be entitled to access their games all the same.