The value of Bitcoin is highest among all the altcoins and it is still increasing at a very fast rate.The only altcoin that has a tendency to surpass BTC in value is ETH .It is just because  of its growth rate in past few days but the chances are least or we can say it will take many years to surpass BTC in value . The demand for Bitcoin is increasing at a very fast rate which is increasing its price and making it the best investment asset.So i dont think any altcoin will able to surpass BTC in value.