I guess never, Ethereum is no doubt the shining Crypto of this era, but keeping in mind, Bitcoin is the Father of every Cryptocurrency. Ethereum can never match its prices or ever go up like Bitcoin because of its infinite supply. It took a long time for Bitcoin to come up to this position and I am dead sure, no one can replace it at least for next 5 years, unless and until something like Bitcoin comes up. Ethereum has its own special features, but the problem of clogging remains, which creates problem while transaction.