each year bitcoin price rises about 150% to 250% if we think of it as a percentage wise rise then you can see how price can get there. i don't say it will by 2020 but it can.
even if price goes up 2x (100%) each year price can be worth that much by 2020.
That's wishful thinking. You can't just assume that because of how the price has gone up in previous years, that it will happen exactly like that once again. I prefer to maintain a more realistic look at the market, where I don't discard the possibilities of a long stagnant period, or even a long bear market. Don't forget that something needs to be done about the block size, which as long as nothing has been done to come up with whatever 'solution' (which I believe to be Segwit), then it will play an important role that may even prevent Bitcoin from growing further.
