I don't see bitcoin being replaced by any coin in the near future. The strong bubble already ended when the bitcoin's price fell from its peak to almost 50% down at 8k$. There isn't any coin with as much potential as of now, but still if I had to name one such coin, it would be ETH.
Most of the ICOs are hosted on ERC20 tokens and the rising popularity of ETH make it a suitable candidate for being the second best coin.