I don’t even think it is necessary to save them specifically.
The folder system will not be deleted. I’s just that Steam will switch the beta off and the live game will then overwrite existing files on the 5th. of November.
The main reason blueprints might not work is, if FDev finds an issue with them and has to change the system. Then our blueprints might not load, no matter where they were saved.
But having a backup never hurts, of course.