i don't see any reasonable reason if altcoins will replace bitcoin my friend
if you watch the market carefully, the rise of altcoins was driven by the rise of bitcoin
This is right form experience in 2017 also. The bitcoin bull was the reason for altcoin bull too. From what op has said, I'm not seeing altcoin so far to replace bitcoin. If you check the strength of the market and capital market, you see no equal to bitcoin.