Thanks for that.
I guess if one was happy with their camera and planned on using it for
10+ years it would be wise to get the latest firmware and keep it as a
backup and re-flash it on the camera's 10th birthday :-)

J. Clarke wrote:

Retention times for flash memory are typically given as 10-20 years, the
issue is that data is stored as charge on a capacitor and eventually that
capacitor discharges to a level at which ones and zeros become
indistinguishable. It may be longer or shorter though for particular
devices depending on the purpose for which the design was optimized.

For more specific information it's necessary to know the manufacturer and
part number on the chip.