Now the mainstream currency, BTC-ETH, has the upper hand, and they have the strength and technology, but the future is likely to be a new project to replace them more mature and more comprehensive. What do you think it would be?
There will be no new king, because bitcoin is still king and will rule for the next few years. Many altcoins, especially Ethereum, have tried the best ways to beat bitcoin, but the results are the same, it is very difficult to take areas that are already controlled by bitcoin.