The satscard is a good product but I don’t trust it as a “keep it until you retire” gift. You need an app or some scripts to access the money and there is no guarantee that the app will be still there or the script will be accesible or even executable in whatever compute we have in 10 years.
Discussion
Yeah, I think a metal backup plate (or a number of them) works well for this. There could be a single sig plate for each heir. Obviously, there are security issues without multisig. I think the dance between hardware and software is an annoying one when looking out 10+ years.