In short I agree the old Bastard is right.
We are going for 6 digit figures for sure.
And even if its not 500k and its 250k whats the difference for investors of 2017-2018. 
250k?

The problem is not the price since bitcoin has the potential to reach almost any price since it can become a substitute to all the fiat of the world the problem is the short amount of years in the prediction, if the prediction was in the next 50 years then I could think there was a chance it may happen but in 2020? That does not sounds possible.