If those students weren't there it doesn't mean they'd automatically be replaced by local students, there might just be fewer students in class overall. Look on the bright side: it's an opportunity to learn and practice what's possibly the most useful language apart from English, and the language of the future as China's industrialisation continues (due to its far larger population, even with e.g. only half the per-capita GDP of America it will still be a much larger economy). Baidu is already leading Google in computer vision. Quite a few of my friends in university were Chinese, and on average they seemed more interested in study and less interested in just boozing their way through university than the average western classmate.