BSC is currently very well prepared to deal with such flows even though Ethereum is unlikely to get very low gas fees with high dex volumes on ethereum and very high ethereum prices for now, I am very optimistic that the BSC platform will continue to survive even if this happens in the future and will remain the choice of many investors to trade on the BSC platform.
Ethereum was also a cheap alternative to bitcoin a few years ago, but now it is sometimes more costly to use the ethereum network than bitcoin blockchain to transact. I for ine believe that BNB is not that popular even now and sometime in the future when it get enough popular to compete with ETH then also there would a problem arise related to high transaction fees on BNB and then people will again look for a cheap alternative just like now.
It is precisely what makes gas costs more expensive, due to the development of the coin being more in demand, the more developed the coin is, the more expensive the gas costs will be, as well as BNB, if later he is able to be in the number two position on coinmarketcap, then automatically Ordinary gas will adjust to the needs, it can even be more expensive than Ethereum gas costs, so it's no wonder why gas costs are expensive for Ethereum at this time.