Flash storage has a certain maximum number of writes and so will eventually fail as a reusable storage medium. But if you simply want to back up old photos, then you are still likely to be able to read back from the medium for much longer than 10 years.

Dell says you may get as little as three months in storage from an SSD:

http://www.dell.com/downloads/global/products/pvaul/en/Solid...

I know someone who had their files vanish off a thumbdrive in the space of a few months of storage.

Every reference I can find gives about a maximum of 10 years as the on-the-shelf, unpowered, lifetime of flash memory. Do you have a reference to some other number?