Ethereum continue to be the most popular altcoin which give people a lot of different opporutunities. So it is very difficult to say that altcoins are dead.
Not only etheruem but there are also lots of other successful altcoins because of which people are in profit and once altcoins gets dead then only bitcoin will be there for investment. People often wants to invest in altcoins because they wants quick profit which bitcoin cannot offer.
Altcoins cannot be dead because new and new altcoins are emerging and they are all very successful from the start so as the time passes there will occur more growth in their success.
Dump does not suggest that altcoins are dead so invest during dump because Ethereum is the king of altcoins and even other altcoins become dead it cannot become a dead coin.