replace the bitcoin is not an easy thing. another altcoin even the most approaching like the ethereum has already lost the opportunity for it. need to be altcoin with a good grid and certainly better than a bitcoin can substitute for bitcoin. but when it happens there will be big changes also in the value of many existing cryptos.
Replacing Bitcoin is not only an easy thing but senseless. Why would we need to replace a good coin? With which alternative? Are there any other coins that made crypto revolution and made history? We need more coins like Bitcoin and not replace what's good.