They are big but it can put a dent on them. Worse thing can only happen if they can not defend their selves anymore. Yes it can take a long time, take XRP case for example but many are glad that they remain to be a victor at the end. Even though it won't be solved completely,
I think the coin can still benefit from the positive happenings that are about to come so we can still invest on it now. In the case of BUSD, Binance already noticed that people should withdraw. But if they can't do it on the designated time, then they are in trouble. BUSD won't bust for now because it's not a volatile crypto but it may stop operating soon. Once all the people convert their token.
BUSD removing in Binance seems not problem for BNB price in the future because Binance already replacing with another stable coins pair from FUSD or TUSD, actually Binance support convert without paying fees and all user have BUSD assets not worry with several months left and keep stable price of BUSD make us comfortable although will delist in Binance. For protecting if price drop later its worth to convert BUSDT assets with other stable coin although Binance have been guarantee with their stable coin can't manipulated like USTC, I hope when BUSD are removing in Binance give positive side for BNB raise to higher price, have been long term for BNB and more than 5 months after dropping price BNB still can't move up to higher price again.