ETH will reach $2500 when bitcoin does to $100k. I don't see ETH going to $2500 in the next few years unless bitcoin goes parabolic. Too many ICOs are selling ETH which will depress its price for some time. ETH is a good token but it needs to consolidate above $1000 before it can go to $2500.
it depends on how the alts will remain tied to bitcoin in the next few years. I really dont see eth reach 2500 this year or next year, but maybe in a few years the relationship between BTC and the alts will have changed completely, with bitcoin at 50K and less than 30% dominance
if ethereum reaches the level of 2500 $ it is extraordinary,
ethereum will reach the history of a new level with the highest increase,
but it might not happen for next month
ethereum will already reach history but it wont be because of its price but because of its implications, also tons of other coins will have seen bigger growth.