It is still difficult to predict how much bitcoin price will reach in December 2019 because we cannot see what will happen in the future. We could only draw a line and predict what will happen later. Besides that, we don't have to be panic if somehow bitcoin price is down or up because if we decide to buy bitcoin and hold it for a long time, we will wait until the time comes to sell the bitcoin in the price we want.
Each person's predictions are different, because they involve parameters used and analysis based on situations that occur in various countries. But there are similarities in the analysis that bitcoin prices will continue to rise until December this year.
I think the price can continue up to USD 20000 until December because positive signals have emerged, both from large companies and from economists who pay attention to Bitcoin.