Thanks for commenting!
Mandarin is of course an important and interesting language. And moreover, it has growth potential.
But the international language is by far English. 
As a L2 Mandarin is predominantly learnt in Asia. Yes, in the U.S. it‘s also learnt. But to what level of proficiency and what percentage?
Be that as it may, I can‘t see for the moment that, for instance, a Japanese and a Spaniard will speak Mandarin when they meet each other, let's say, in South Africa. However, that‘s what it takes for a language to be considered as an international language, at least for me.
Let me know what you think about it!