I highly doubt that ETH will be 15k or even 5k in this year, most likely we can land somewhere between 1000 - 1500$ for Ethereum.
This huge predictions are making no sense now, but i do believe that in near future, maybe in the next 2-3 years these prices are possible.
Ethereum has 2 big milestones ahead in 2019 - Casper, and 2020 - Sharding, i think when ETH will also be limited and there will be only POS mining, price will definitely go up.