I think that things have just worked out in a way that English is the most spoken language in the world. Mandarin Chinese is the language with the most native speakers, but if you could all speakers, then English takes the cake. I think has changed over time. In some period Greek was a big deal or Latin. I know that French used to be a much more significant language. I'm sure at some point English could die back a little, but it doesn't seem like that'll happy anytime soon. I think it's highly unlikely that Chinese will become a huge international language, though the Chinese economy is huge. It's a much more challenging language to learn than English.