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.
I dont believe that bitcoin is replaced by other cryptocurrencies because as of now. Bitcoin is popular in many countries and becoming more popular as the time goes by. And also. For me. Bitcoin is the most trusted cryptocurrency. And its value is high than others.