Bitcoin will never be replaced imho... not in 100 years not in 1000 years.
Bitcoin is the only truly decentralised cryptocurrency. Ripple is completely centralised. Ethereum is too much centralised (I'm not talking about mining)...
Litecoin is a copy of Bitcoin with a different algorithm...
I don't want to talk about EOS, Tron and other shitcoin because they sucks too much.