Another currency or another altcoin? If altcoin then Lets wait for etherium to replace the throne of the king if bitcoin will not implement the lightning network and etherium will in the future successfully feature it Im sure eth will be the next one.
In my opinion, it is very difficult for ETH to beat BTC, if there are a lot of other coin apps that are better than ETH and BTC. However, the difference is that people only believe in bitcoin because their prices are not so volatile