I don't see this happening. It could happen maybe in 100 years time when cryptocurrencies are as easy to spend as our fiats today but realistically, BTC has always maintained a little over and under 50% of the total market capitalization of the cryptocurrency market.
With The 21 million total supply and 18million btc already mined so far, there will be more scarcity and this will increase the price more.
I cant see any cryptocurrency taking over BTC as the top cryptocurrency in the Blockchain space.