I dont think bitcoin can be replaced since it is the mother of the crypto world. Maybe in the future, it can be innovated and improved but i dont think so it can be replaced to another cryptocurrency. It will be a lot of hardwork and time to be able to replace bitcoin.
The possibility is always there but we cannot say that possibility will happen easy, if you take a look on what bitcoin have already achieve you can tell that we have a strong foundation over here.
It take so long to reach this status and the longer it exist the more people trust it, so definitely it's hard for bitcoin to be replace for the new one.