With a marketcap of more than 45% it will be difficult for any coin to replace bitcoin, and I'm sure that the future of bitcoin will continue to improve and it's hard to replace it with another coin for at least 10 years from now.
Bitcoin holds most of the market share within crypto land, but has been slowly decreasing over time as other altcoins have taken the lead. Bitcoin had a higher share within its early days, but since it has been experiencing scalability issues lately, other altcoins have risen in popularity and market share. However, once Bitcoin adopts the Lightning Network, it might increase further in value and demand, allowing its market share to rise over time.
Unless, another cryptocurrency with better technology and acceptance than Bitcoin comes in, it'll be difficult for the King of Cryptocurrencies to be replaced soon. Bitcoin already has market recognition and first mover advantage. As such, it would take a lot of effort for another cryptocurrency to take the lead and overcome the pioneer cryptocurrency in the future. In the end, Bitcoin will continue to grow and expand into a full-fledged cryptocurrency capable of handling all the world's payments. Of course, there could exist a possibility of another cryptocurrency overcoming it (perhaps a centralized universal cryptocurrency), but until then, Bitcoin will still be the King of Cryptos for quite a long time. Just my thoughts
