The problem is not much different than "facebook", "reddit", "ebay", etc; it is all about userbase, and trust. Even if some shit coin was vastly superior to BTC you would have to get people to start using the new one. Personally I don't see this happening unless a fatal flaw is found in bitcoin. I will also add that decentralization is very important for crypto as well, and many other coins are not fully decentralized.