When all currencies will be done away with and every one in the world will be forced to use only Bitcoin, there won't be any fluctuations! For one simple reason: - there will be nothing to compare it to! Everything else is going to be outlawed and the only legal worldwide exceptible currency that's going to be allowed and exceptible to use it as currency is Bitcoin. Nobody going to be asking your or mine opinions on that matter. Bitcoin stands out as perfect means to use it as value transfer, it's digital, it's traceable, you can instantly send it anywhere in the world, you don't have to carrying it in your pocket or suitcase, you don't need to build fortified vault for storing it and have enhanced armed security guarding it which has enormous expensive cost for all of that, you can't conceal or hide or falsify any of the transactions, it easily devides into the smallest fraction and the most important one is anyone can be blocked from using it and it means that all those who will be using it will be fully controlled completely. It will be controlled not by individual but rather by someone else at centralized control center who will be allowed something and how much and who does not, period. And if anyone dares to turn slightly off of projected path your account gets blocked and their it is. The only choice one will have is to always comply and obey and there will be no other way. Today if you loose internet connection or blocked from internet - you can't use Bitcoin or anything digital. The good part of it is that crypto is easy, fast, convenient but the bad part of it is that at some point in time you completely loose all control over it, and that means you COMPLETELY lose your FREEDOM.