If you ask me, it will never happen at all, because ETH is not strong enough to fight Bitcoin for first place in the market. Personally, I think Bitcoin will always be number one in crypto...
At present, there is no crypto better than Bitcoin. honestly, I have seen many altcoins trying for it, such as ethereum, BCH, BSV, XRP, and others, but until now, in terms of price, even needs, bitcoin is still in the top position. Well, I don't think that altcoin will be at the top of the crypto for this year, even for the next year.