They will all survive. These two coins will not disappear in the next three years. EOS's growth may surpass Ethereum in the next three years, but they are not my favorite coins. I will not invest.
I agree that both of them will definitely survive because they have an important role in crypto because they provide the platform used in new coins so I'm sure they will continue to be used.
and in my opinion even though you don't invest in both, but at least you have an ETH and EOS wallet because now there are many ICOs that demand that we have an EOS wallet.