Crazy idea - if you're paranoid enough, could you print your BTC on real metal that could last as long as our physical currency does? It loses its liquidity, but it gains permanence.
(Not the original poster) I suppose it's cold storage, but on something which is more permanent than paper. Of course it's a bit pointless since even the cheapest most acidic paper should last for 20 years or so which is long enough for storing bitcoins for the vast majority of funds.
