There's no doubt bitcoin can reach up to $20,000 but 2019 may not be it, given the current situation it's in. It's almost the end of the year, yet bitcoin's price still plays around $6k. It will take some miracle before it jumps immediately to $20k next year. But maybe it will rise gradually, maybe even $10k but $20k? We can all just hope.
I think bitcoin will start to pump by the early month of 2019 and hopefully it can hit $20k peak, as what most people desired and waited for this long months. Patience is the high recommendations to acheive what we aim for.