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.
It is hard to tell, however there is nothing is impossible. In the future if someone who is able to make much more better than bitcoin then it can be replaced, or another factor is if bitcoin wont adjust itself in the future and fails to make innovation then it can be replaced. like what happened in (Yahoo and Nokia)