As bitcoin continues to grow, as it likely will, the unit of account aspect will become more and more stable too... But there may likely be another 10 years or more of bitcoin growth, including likely 1000x or more price increasing in bitcoin that will also bring more and more stability in its price... in other words, the instability in bitcoin in the next 10 years or more... and perhaps even more than 20 years, is going to likely be in the upwards direction, merely based upon ongoing and increasing adoption... that is seeming nearly inevitable.