USB flash drives generally don't have good lifetime unless they are industry graded, so I would not trust them as only backup option for storing bitcoin keys.

There is one interesting new drive Blaustahl USB, that is based on FRAM (Ferroelectric RAM) that could last up to 200 years, but it can only store 8kb of data, that means only text files.
https://www.tomshardware.com/pc-components/usb-flash-drives/this-usb-flash-drive-can-only-store-8kb-of-data-but-will-last-you-200-years