To defiatize the unit value of bitcoin at this time or even on the next five to ten years is next to impossible. we always need something to measure its value. In saying that the valuation of one currency is not correlated into another currency is like saying that import and export is not existing.
It will be a long process, maybe will never happen. Bitcoin is deflative and increase in value constantly, it is difficult to act as a unit of value
Energy can be used as a unit of value, like Joule. Energy can always be utilized in modern society to do some work, so its value is relatively objective. However, you can't store and circulate energy directly, so something that is produced mostly by energy will act as a token of corresponding energy's value
Since most of the time Bitcoin's value is closely related to the energy that used to produce it, using bitcoin as a token of energy will make it close to a very objective measure of value