Let me introduce another variable. Maybe it's a gradual end of BTC, but in a way that something else takes it place. Like it happened with social media (and is happening still). BTC might not go away completly, and still stay as a store of value, but something else takes the top spot.
However this might happen in future but currently this seems not to be the case. Bitcoin is most decentralized across all the digital currencies and it will remain to the king of cryptocurrencies.
It is already proven by the time. Since Bitcoin is created, no other cryptocurrency has been able to surpass Bitcoin.
Just think of a lot of companies that are already into Bitcoin, individuals and companies who got billions of their funds into Bitcoin and I don't think something else will take the top spot. Bitcoin is perfect for the top spot.