I'm not sure that Bitcoin will replace fiat. I do not see any sense in it. Bitcoin has already taken its place in the economy and in the life of users. Why do we need to Bitcoin replaced the dollar
You are absolutely right. Although the bitcoin user continues to increase, it does not mean replacing the existing ones. We should know that many of the countries that made the dollar as a second currency so if replaced with bitcoin then many problems that occur. And the most important thing is marketcap, dollars are the largest, maybe a hundred thousand trillion while bitcoin still in his teens billion.
Bitcoin cannot replace the United States Dollars and it will never be. And in line with your thoughts it is clear that bitcoin will face many problems if it will not be backed up by fiat currencies or by dollars. Bitcoin is good as it is, it does not need to replace dollars and became stable in price. If bitcoin will not replace dollars it will continue to rise in value and that is what we all long for.