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?
BTC-ETH pairing is the most higher volume in trading and I don't think that this will end-up easily. Even if many new coins will come this will not make a threat to bitcoin because Bitcoin will remain as the main currency in cryptocurrency as all price of altcoins will be affected with the price movement of bitcoin thru algorithm.