Bitcoin can't be defeated I guess because the value of it right now is still biggers than anycoin in the cryptocurrency markets and even though the value of bitcoin today is not regular and not maintain it is not even close that bitcoin will be eliminated nor defeated by any type of crypto in the market. 2019 will be a good year for bitcoin I wish.
In the coming years, bitcoin may not be beaten. But if we already judge by what is happening now, then more and more people prefer Ethereum. Therefore, on the air, all shans win.