Altcoins aren't a single coin so there is no way that all of them will die but many of them are now dead because they are weak and scam. Good altcoins can suffer from a bearish market but being dead isn't the best way to call or term them during these times. You can't call something dead if they are still active and can recover by the time the bull season came in, and also it was the new coins who has more chances of dying because new coins usually don't have anything new to offer as almost all the ideas are already given by the old coins. New coins are only good for the hypes so we can still invest on them for short-term gains.
That depends on which altcoin we're talking about. If we're talking about "meme" coins, then most of them will eventually die after people move on to the next big thing in crypto. Such coins are only good for short-term profits, due to their highly-speculative nature. But if we're talking about new coins with innovative features (especially smart contract platforms), then that's another story. These coins won't disappear that easily, especially if developers continue to "bring in the goods" to the public. Be aware that not all that glitters is gold, so I'd advise you to do your own research just to be safe.
For what I know, investing in altcoins is a gamble these days. Most of them don't take things seriously, as they're usually driven by hype. Only a select few altcoins are really worth your time. One thing for sure is that no altcoin can survive without Bitcoin. If BTC goes down, so will the rest of the other cryptocurrencies in the market. Just play your cards right and you'll have nothing to worry about. Just my thoughts
