When I was living in Australia, all the hype was around Anthony Mundine and his was quite a story being a top Rugby league player then being a WBA world champ. I honestly don't think I'd have ever heard of the guy if I hadn't been living out there though, nobody I know in the UK has heard of him. Got me wondering if the same would be true for some british champions? Would the rest of the world know or care?
Althogh it's impossible to speak for other boxing fans, in other nations, I'd say you've got a good point, and that it's highly unlikely our domestic fighters will be (well) known around the world.
I think that in order to become a global star, you have to make a name for yourself/or stand out from the crowd. And there are various ways you can do that, but whatever you do, you obviously must be talented. For example;