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.
If BTC crashes down, so will the altcoins. Because when I looked at the market, altcoins always follow Bitcoin. Bitcoin will always be greater and being crashed down is most likely never because they have the most trust. Altcoins are not independent.