No matter how many coins will launch in the market, the Bitcoin will still dominating the crypto space, no matter how hard the dev tries, they will just behind the Bitcoin, it is the king of crypto and nothing could beat or replace on its place.
There is no guarantee that Bitcoin will never be replaced by a technologically better alternative. As the case with all the technological innovations, Bitcoin also will be eventually replaced by something else. However, right now there is no such alternative in existence, which has the capability to overtake Bitcoin. There are technologically advanced cryptocurrencies available, but their basic concept remains same as that of BTC.
If a developer wants his coin to replace Bitcoin, then he should be ready to try a fundamentally different approach. He should be able to come up with an alternative to Blockchain. As of now, almost all the cryptocurrencies use some form of a Blockchain to store the transactions. And since it was originally a concept invented by Satoshi, Bitcoin remains on the top as the "original" cryptocurrency. It is possible to replace Blockchain with a better concept.