I don't think that it will reach 20,000 dollars price that much soon.Earlier it was due to launch of bitcoin future sfor such an ATH and now there seems no such possibility.But we could hope to cross 10,000 price soon and it would definitely be a great bounce back from 6,000 dollar price.
Maybe by the end of 2019 it will get to 20k with steady growth. Only steady growth, big price jumps play out bad in the long run.
You know we are in the early months so I think this year price will moon to $20k. It is possible this year 2018, with the recent growth it is slightly in the mood to go up. So let us see the price and observe it will bounce back to all time high.