I am sure the owners of the site would have no problem in expanding the scope of the site. Where this issue comes in is marketing to other countries. It is very hard to make a site that is appealing to countries around the world. Part of what goes into rankings around the world is your domain name, location of hosting and the like. So if you were to do a search for a particular topic in New Zealand you would get a different result than you would if you did that same search from within the US. So trying to get traffic from another country would become an issue. If a set of forums is setup to deal with New Zealand just as an example, you might get someone who posts a question under ask a cop and never gets a response because the only people who would even consider looking in that category would be people who live in New Zealand. This would drive many people away from the board.
I would love to see a regional board but I don't see that coming for a while with this board.