An interesting question, of course, but it is definitely impossible to answer it, since no one can predict what the market will be in the future. But according to Coinmarketcap statistics, it is clear that Bitcoin, Ethereum and XRP are leading
If cryptocurrency gets the chances of surviving, I think that bitcoin will be the main coin that will surely dominate the market and dominate all currencies because right now, it seems like it is the one that is the major coin that people have really relied on, when it comes to fiat system, bitcoin technology supersede them, and when it comes to cryptocurrencies, bitcoin is still their king.
Since Ethereum has been establish, they even came with the intention of sending bitcoin away from the market, but now, people would rather prefer to make all their transactions through bitcoin than to make any through Ethereum. If we are looking for an alternative to bitcoin in future, I think that is when we can think of making use of Ethereum s the alternative because we don’t have a choice.