BNB will never be a replacement for ETH, since ethereum has a completely different purpose, creating smart contracts on the platform, which BNB cannot do, Ethereum is paired with all the exchanges I know, it has 2nd capitalization and 2nd place in terms of trading volume, as well as a large the audience.
I don't believe bnb will get better than eth too. As a matter of fact, I think Changpeng Zhao has over worked himself lately to get CZ to the high it got this year and its current price is not just an indicator of general bad market state but also a reaction from investors no longer buying the bnb hype. I understand it has numerous legitimate usecases but then it really needs more to beat Ethereum blockchain utilities