The word "Alt-coin" should mean "Alternative Coins". And the word alternative in a layman's language should mean having an obvious option. Example, having an alternative plan means I can decide to use Plan B, most especially if plan A may not favour me at that time. Also, Coffee is an alternative to Tea, in this scenario, alternative is a choice and not a measure of importance. In a situation where an alternative is a choice, is therefore means that the Sorrow of one will be the pleasure of the alternative.
Relating this to cryptocurrency, if BTC who is the mother of Cryptocurrencies and who has gained extensive trust ceases to exist today, will altcoins flourish or will it make the people loose total interest in cryptocurrency.
It will make people loose interest as btc is recognised as no. 1 on the crypto market. It is mostly acceptable among every other coins around the globe, meanwhile a lot of development has initiated under it example like the BTC ATM etc.. So I think other altcoins will cripple to dust once people loose total interest on its mother BTC.