The DAI protocol does the supply control required to keep it stable. Evidently, it has managed to hold close to $1.00 even through very volatile phases.

All STEEM has to do is manage its debt to DAI. Which, yes, will require a paradigm shift, not ramping up DAI purchasing when the price pumps temporarily, etc. All of this is just throwaway thinking-out-loud, of course, and I'm well aware it's not going to work for multiple reasons with Steem in its current state.