It has being used as payment means for goods on the long run and that has being an innovative system at the moment but the knowledge and usage of Bitcoin has not fully being diversified making it not fully functional.
But here is the question, do you think Bitcoin can overshadow the relevance of dollar in the future?
For now, the possibility is still small, even impossible, and honestly, I doubt that something like this will happen in the future.
This doesn't mean that Bitcoin's progress isn't good, because regardless, their development is truly excellent at the moment. However, defeating FIAT is clearly not a goal to be achieved, because from the start, this isn't a competition but rather something that can coexist, where Bitcoin is projected to be an option, not a replacement.
Even if it were possible, the main goal is not that, so we shouldn't expect much in this regard. Besides, many people, including the government, would not want this to happen. Furthermore, I prefer Bitcoin to remain as it is now, where its use is still very flexible.