Bitcoin will stat on top of all crypto currencies but this does not mean that crypto will remain forever. Who knows after 100 yeas there might be no signs of crypto currencies and bitcoins.
How can you say that?
I am not saying that it is impossible, it is possible but saying that there will be no signs of cryptocurrencies in the future? I think that is impossible. One of the greatest technology Bitcoin has is the Blockchain and a lot of people are speculating that it will be widely used in the future and not only in the market we are used to.
We cannot actually define on what will happen in future since he have a point we don't know if cryptocurrency and bitcoins will last for that far since anything would change day by day and maybe there are other forms of E-currency will launch to compete the cryptocurrency in the market, but in other though if bitcoin will gain huge adoption and will break to legalization then for that we can say that bitcoins would last forever.