^ Agreed. Revisit your stuff over time to refresh it onto newer media (& to check that it's all still intact in the first place!).
As for using SD cards as extended-life storage: the comments above align with my thoughts; it's not worth it. I definitely don't think you'll immediately lose data, but when something like an SD card dies, it tends to be pretty thorough in its failure. Something like an SSD might work a bit better, due to increased design tolerances and durability. A USB flash drive's design could fall anywhere between the design of an SD card & the design of an SSD drive, but at the end, that too is designed more for day-to-day use with plenty of read/write cycles but a not-so-great life expectancy.
For extended storage, putting the contents onto a magnetic drive as well as optical storage for immediate, speedy retrieval would be my preference, with a decent look into cloud services when time/money/Internet connection permit its use as a viable medium (should things be that important to you, without any major security risks posed by putting your things on a remote server).