Bitcoin prices are going up and down these days. People are hopeful that the price of Bitcoin may well go up by 2021. Bitcoin has been legalized in a number of countries, due to which Bitcoin prices are now recovering. If the price of Bitcoin goes up to 25,000 by 2020, it will be very difficult to buy.
Its not impossible. I can also occur at a later year. But the longer it takes, the steadier it is. I think after halving, whatever price it gets, it might come a period of either sideways or bear, depending if the was a bull run or not. Sure it might mean a higher price in the end, but that is how it would fluctuate in my opinion: Average price should be higher than the same period before halving. How high? Not exactly twice, something between previous average to twice that without actually reaching twice.
So if avg was 7k it next avg should be under 14k. Unless something important occurs (has happened before). But the tendency is for bitcoin fluctuate less and less overtime. The highest gains were at the beginning, in the very early years and it can never return to that.