I cherish Flyertalk's global reach.
I don't think we need to worry some much about the geography of where a Flyertalker calls their home airport, as much as whether or not they have a provincial or global outlook, and perhaps whether they actually travel the world or not.
Looking over forums created while I've served on TalkBoard, I believe we've created more for non-US programs and locations than for US ones. And that's likely a function of Flyertalk becoming more and more global, when it started there were more US-centric folks.
But the criteria for forum creation, in my mind, is whether the forum will generate enough activity to be vibrant rather than moribund. If people come to a dead forum, they don't return. And if they don't return there won't be new posts and the next person finds a dead forum as well. It's useful to draw a circle around posts and put them in a particular forum when that'll help people find information or create a place that's focal where a question will get answers from the best-informed people because that's where those people congregate. But creating a little-visited forum harms both of these goals.
So as Flyertalk grows, the specialization in forums will grow. And much of that specialization has grown in non-US areas.