It was discussed earlier in Steem's history that if the US dollar were to seriously go off the rails the Steem community could decide to peg SBD to something else such as precious metals, a basket of commodities, etc. This would not require code changes, just agreement by the witnesses to start using a different data source for the price feed.

The Steem fork/copycat site Golos used gold as the basis for its version of SBD.