There are many cryptocurrencies out there, the fluctuation is wide and big. Theres a need of a coin that uses a process to stabilize its value.
No doubt that there is no other cryptocurrency or altcoin that can supersede the bitcoin. At least not for the next 5-10 years. Of course there are many rising competitors like Ethereum, ripple and litecoin.
Do you agree???
I think you should avoid that overconfidence. There are no compelling reasons to think that bitcoin can hold up as the most important cryptocurrency in ten years, when crypto technology has reached such advanced levels that it will make all the cryptocurrencies that exist today seem obsolete, and the level of use and the adoption of cryptos make the use of bitcoin excessively expensive due to its scalability problems.
One thing I am sure of: bitcoin will continue to be very popular in ten years and it may still be an important store of value, but due to technical specifications it is likely that the cryptocurrency used for daily commercial exchange will be another, and perhaps this has not been invented to this day.