There are hundreds of exchanges that can replace Cryptopia.
Cryptopia was a very small exchange, most of altcoins, that was listed on it, more likely will die. I think soon many low cap altcoins will migrate on Binance chain and their DEX.
I do not think that is gonna be as easy as you think. Binance does a lot of research before listing any coins, and that should be another reason for being the number one.