If to replace the position of bitcoin, I think it will be very difficult, because they have to make a lot of changes and the development of the technology they have, not yet the level of performance. But if for the position of Ethereum, there are still many possibilities to be replaced. Ethereum is only the king of the altcoin, where the position is uncertain to be ethereum forever. If there are other coins that are more capable and superior, they have the opportunity to occupy positions under bitcoin exactly.