Cardano is a great coin with potentials but cannot replace ethereum at least not yet, does it have the kind of platform eth has? Can it provide the smart contract platform eth provides to other tokens and coins? Cardano on its own is still dependent on ethereum. Like someone said, if Cardano is to replace ETH, then the price should increase without depending on ETH rather it should depend on  Bitcoin. Well, maybe in the future it can but definitely not now.