One thing that worries me though about things like this is that electronic hardware always carries a risk of failure which increases over time. I've never trusted hardware wallets because of this.
You make a fair point.
Satoshiums based on Java-card cryptoprocessors properly housed in a protective enclosure should have a fairly long shelf life because they remain inert and unpowered with no built-in power source, but only activated by an NFC interrogating device or a USB connection.
We address various hardware-failure scenarios including aging and Carrington Flare type events in the section 2.1 of the white paper.
Let me quote the relevant passage:
2.1 Security Considerations: Satoshium
A satoshium should have a shelf life of over a decade if it is heavily circulated, or longer if it is
sitting in climate controlled storage, however just as cash can be burnt so Satoshium can be
mechanically destroyed, therefore users should consider redeeming very old satoshiums.
There is about a one percent annual chance of a Carrington-type solar flare event that would
damage unprotected electronics on a worldwide scale. So the enclosure should include faraday
containment of the cryptoprocessor.
The standard answer given by hardware wallet guys is that once you made a backup,
the hardware of the hardware wallet is nearly disposable because the wallet is fully recoverable from a
paper or metallic back up.
Satoshium has something we call "Secret Extraction" it's not meant to be a backup in the same way as hardware wallets,
but rather it's an advanced feature to deal with various edge case scenarios, one of which could be aging or various types of damage.