It's almost 8 months of 2018 and we have not seen any reasonable hikes for the altcoins,
It was only Ethereum that hit a good value of almost 1.4k$ in the beginning of the year . Since then it's pretty dull.
Forget overtaking can any ALTCOIN ever reach a value near Bitcoin.
With this current market performance then we have already seen that there is no Altcoin can supersede Bitcoin. Bitcoin price is declining that it will be the opportunity of every Altcoin to step up but they have waste the opportunity as they also ride with the Bitcoin bearish performance therefore we can conclude that Altcoins are depending of Bitcoin performance that is why its impossible for them to replace Bitcoin as the number 1 Crypto in the market.