its possible a fungible coin like monero (XMR) could take over.
First of all what is your proof that either currently bitcoin is not adequately fungible or that bitcoin is going to become inadequately fungible?
Second, regarding a "possible" Monero take over, are we talking realistically? How would that happen, by mere hopium? Is there some kind of actual Monero superiority in comparison to bitcoin?
For now bitcoin can still be used freely. there is no coin that fungible to match the popularity of bitcoin. as long as bitcoin is still in line with the times. there will be no coins that can replace bitcoin later.
let alone monero. I myself have never invested in this coin. so in my opinion there is no chance at all monero replace bitcoin