Well based on the price of bitcoin today or this year it can't be replace by another cryptocurrency,, actually it can but it will take a decade just to replace bitcoin in its place, every time passes by the bitcoin price is increasing too meaning it is impossible but in other side it is possible too
I do think that based on the price, no other digital currencies will replace bitcoin. It's price is so hyped right now that it made many people a millionaire. But in terms of other features like speed of transaction and fee, I guess it can't be replaced. The thing about bitcoin is, it is a good investment the reason it will never replaced.