Not so easly to replace bitcoin. Because bitcoin is still dominating the market and bitcoin is really have the highest rating also the most trusted by a lot trader / holder. But in crypto-world everything is possible. But that too hard possible happen.
The main reason many want to replace bitcoin is because they think that if bitcoin is replaced their favorite coin is going to take that spot, what they do not realize is that the disappearance of bitcoin will create instability in the market like we have never seen and this will crash the market, we have seen the market of crypto crashing 85% or more, what do you think it is going to happen if bitcoin disappeared? The market will crash 99% at least.