As far as I can tell, the only way to back-up your hosted feature layers is to go to each one's "item details" page and click "export" and download the FGDB. What if I have 50 hosted feature layers? I have to go to each one individually and perform that work flow.
Can Esri implement a "back-up" button or a "download all" button?
For backing up web maps and apps, I don't think I have any options, at least not built in. How about some tools built in for this too?