It defintely will crash and burn. Okay at least crash an never revisit those highs, remeber that we have has similar situations with bitcoin cash and btc.. the eth fees will go down and the bsc will lose its relavency.
It seems that the BSC will not just disappear when ETH costs have decreased and stabilized at a low rate, because they are basically on a different path so that investors and new project developers can make the choice of which one they will choose for their business.
I have emphasized enough that not only both Ethereum and BSC are here to stay but we will see other chains like DOT and ADA to be the part of smart contracts. All of them will co-exists which will be good for the overall crypto community. All chains have some advantages and disadvantages but they will continue to improve in order to take lead over the other.