Let's project.  

If we assume the average doubling floor time of 6 months over the last 5 years (including the 2014-2015 bear market):

$20k Aug 2018
$40k Feb 2019
$80k Aug 2019
$160k Feb 2020
$320k Aug 2020
$640k Feb 2021
$1.28MM Aug 2021

Three and a half more years.

If the doubling time persists at 3 months (the approx. average of the last three doublings), then just under two years. Mid 2020.

Wow.

edit: skipped a year