I believe that ETH will reclaim it's glory back once gas fee issue is solved, there is also a big difference between BSC and ETH that will still make many prefers ETH, that's the fact that BSC is Centralized and ETH isn't.
I think the only reason for the popularity of BSC is its low gas fee. If Ethereum's gas fee decreases, it will return to its previous position. Then everyone will leave BSC and run towards ETH. Because ETH is a coin trusted for many years.