Which ALT coins can replace Bitcoin ? In my opinion, I think: XVG - security coin , XRP - fast transaction.
I think in the near future it is hard to have a strong enough altcoin to replace Bitcoin. The current Bitcoin is very strong, it is the king of all altcoin, it controls all. Bitcoin is popular all over the world, every day it has a large trading volume. However, I believe most people here will agree that Ethereum will be the altcoin that has the most chance to break through Bitcoin. Ethereum is always in second place after Bitcoin. It has very good technology. In addition Ethereum also has many advantages over Bitcoin such as faster transaction speed, lower transaction costs. I believe that in the future, if Bitcoin weakens and Ethereum grows stronger, Ethereum will beat Bitcoin