Seems to be so logical in the way you have made an assumption about the possibility of Bitcoin to rise up its price into a price of $20,000 in December since it have rise up at the time of December last 2017. Though it may be true, we can never tell when that event of rising up the price into that specified amount will happen since we are just waiting for that moment to come. Well, it is really possible to rise up again into that price in anytime around not just only in December.