I don't see any harm in holding altcoins especially in times like this , when all the coins are down like this. If you panick and sell your coins cheap you will regret selling them when they explode in the future. They always does. It is really rare for a coin to completely disappear after a crash. It just take various time for various coins.
Holding your altcoin is somehow a bit of a gamble since its value always changes through time. But as you said, now, the odds of a failure in most of the existing altcoin is very low. Sometimes the value of your altcoin fall because of its less usage, but as long its well recognized its value will start to rise up again.