There is a huge competition between cryptocurrencies, many believe just dynamic and self fulfilling ideas with different properties and a variety of incentives may survive! Others expect fiat money will leave behind reliance on quantitative competition!
I think cryptocurrencies are not able to defeat fiat currencies without changing nations culture and ethics! what do you think?
It is not the objective of the cryptocurrency namely bitcoin to "defeat" fiat because to "defeat" something you need a battle, and there is no battle here. Only coexistance of both modes of transaction such that the pros and cons of one are supplemented and corrective by the other, respectively.

There is in reality very little competition going on. The top position is take by Bitcoin due to its highest price among all and the small fries are being competed on by shitcoins that have no value but still hunted for sudden profits. These coins will never be big.
What most coins lack is an intrinsic market making capability and a method to spend their coins to get some service, only then a market demand will begin and prices will increase of that shitcoin enough to name it an altcoin.