To believe (e.g. to be certain) something like that does not make rational sense. To say that is a statistic probability makes much more sense. However, this has been discussed over and over again. In order for the cryptocurrency space to thrive, it would be most suitable if there were multiple coins at the top and not just one (as currently Bitcoin is). Nobody can say that either one will happen for sure; they would only be speculating.
Bitcoin for now is upgrading and its value increases dramatically so thinking that bitcoin would be replaced by other crypto-currencys thats imposibble for know. We all know that bitcoins value is depending to the support of people so many people continue to choose bitcoin than any other crypto-currency. That is the fact and when bitcoin becomes more popular many buisness will be open on accepting bitcoin so it may be the future ot bitcoin. It cant be replaced by any other. Because bitcoin is just starting to grow more.
Also because we are addicted of using bitcoin and use it rather than using any other currency we are unknown of.
This is the main factor bitcoin will not be replaced !
At some point, Bitcoin might be replaced by a similar currency, in terms of market capitalization. But Bitcoin has a huge user base and this is a big advantage.
Bitcoin is not ready to replace all forms of currencies and fiat money at the moment. The question perhaps is, will Bitcoin be replaced by a better version of it, or by something that is very different and revolutionary; Something that offers many additional features that Bitcoin lacks. There could be some new innovative currency that could have such properties, and that could replace Bitcoin.