How can you sure with that? Currently ethereum value is $660 and it was still growing up. However there's a possibility that their value is fall down to $600 because more investors now are starting to withdraw their amount in some exchange and their wallet. Hopefully that this coming May 2018 value of this coins are increasing and cannot stop. Last year 2017 almost $3000 above the value of this crypto, so I suggest to many users to hold their amount because I'm pretty sure that it will continue increase soon.
In the end of 2018 Ethereum will be around $2000-$2500 in my opinion, unless something really bad happen. We all love it when Ethereum pass $1000 and we all want to see it again. IMO just hold tight and the end of 2018 will be Ethereums time.