For bitcoin, 5 years is considered a very long period of time. Anything could happen like for example total economic collapse which makes bitcoin being taken seriously as an alternative currency. Or the popularity could even fizzle out making it worthless someday. Whatever it is I imagine it could end up either very high by 2020 or even worth nothing by then.
In my opinion by 2020 bitcoin will either have taken over the world and be worth trillions in volume or it will be worth nothing and forgotten about. I'm hoping the former rather than the latter.