As cajun says above.
Please remember that popularity although an important factor in deciding if a phone gets a forum, IS NOT the only factor.
We are likely to see more and more low priced devices around that will be very very popular (due to price) and we will not be adding them all if any!
So in addition to popularity we consider things like the specs of the device, does it have anything particularly new to offer, are there existing or potential developers for the device (not just ROM cookers) and so on. This does mean there will be potentially "good" devices that we will not add. In addition of course we have to have regard to our resources. In today's world we could add several devices per week, but we would not be able to provide enough administration and moderation to keep things running at least fairly smoothly!