in my opinion bitcoin and ethereum won't fall 2 these altcoins will survive because there are still many who still use them. .
maybe bitcoin CASH or bitcoin sv can replace bitcoin these two altcoins are the strongest canidians to replace bitcoin but that is very small because I think bitcoin will be very difficult to slide from the top
Any altcoin that replaces bitcoin at the peak can hopefully be a positive trend to bring all altcoins to the moon