I bet you're right about your target. Honestly I wouldn't be surprised if the growth goes from a linear to a parabolic rate at some point. Who knows if that'll happen this year but if it does we could see over 1 Million users by the end of the year.
I'm pretty happy to have gotten in early even though my profile is only about 2 weeks old. In 3-5 years I'll probably look back at getting on steemit as one of the best financial decisions I've ever made. Imagine when there's 5 or even 10 million users...it's gonna be an amazing ride for sure.