I'm curious - I was with Travel.SE right through beta, and now with Expats, and it's been longer with expats and still in beta.
All of our area 51 stats are currently ok or excellent.
What else is required for us to graduate?
The rules for graduation have changed. Basically:
When a site starts to consistently receive 10 questions/day, we’ll consider it for graduation.
Although from the comments, it seems that they also consider sites with lower questions/day.
The key thing to take away from that post is:
Success and graduation are not the same thing
I think we are successful. We are attracting high quality questions and providing them with high quality answers. Our page views suggests, and some of the other analytics, suggest other people are finding our answers helpful. That said, I am not sure we are ready for graduation, in particular the change to full reputation levels would be problematic. i don't think we have enough high rep users to adequately deal with edits, closing, deleting, etc, if the rep levels were doubled (we only have one 10k+ user).
We need a lot more active users.
We need a lot more reputation being awarded.
We need somewhat more questions w/answers.
If you look at the badges, it doesn't paint a great picture of activity, even among those of us who are active. Sites that have graduated seem to have a lot more middling to high reputation users who just seem to hang around doing fly-by moderation.
We just aren't there yet. And our Meta isn't exactly running over with activity either. I know that probably shouldn't matter, but I have to think that the powers-that-be surely take a look at some of these unstated non-metrics and get an impression from all of that.
Continuing in the vein of existing answers from last year: Perhaps what this site needs is some active promotion with other places on the web where expats are likely to skulk/surf to. I don't mean ads, of course, but rather:
If we were simply to attract more people to ask expatriation-related questions - It would get users who follow tags to become more active; it would get more votes by those people on the answers they get; they would also notice other questions and answers, and vote; and thus answerers will get more reputation and some badges. Which is why it seems to me that's the most important thing to do.