Shamir's Secret Sharing allows this even without dealing with multisig wallets.
Also, it's a fairly well-known system, so I don't see it being collectively "forgotten" on the timescale of a few decades (it's been around since the late 70's i believe).
I'd love to get it integrated into wallet software, as it's such a safe and reliable way of storing secrets that lets you be as "secure" or as "reliable" as you want with just a slider.
2 of 2, 3 of 5, 7 of 10, etc...