According to my research, the average sum a person would invest in bitcoins is $1000. Therefore, 4 million new users are needed in addition to the 1 million current ones to reach $7000.
That seems like a lot to ask for the next 7 months. I think chances are some bigger investment funds are going to have a big impact though.
That is only 25.8% monthly growth in userbase. Which happens to coincide with the long-term slope of the price appreciation curve.
With this adoption growth, without the logistic slowing, we would be at 2 billion people in March, 2017.