I think Mandarin is the way to go. I mean with almost every country vying for the affection of China and its man power and its influence on the economy then speaking the language is a huge advantage on this point. I've seen it first hand how the rights words on the right ears opens doors and create opportunities.
Thats right, China might be a superpower in the next few years, in all fields of economics, industry, and so on. It would be very unfortunate if China's expansion in many countries from various sectors and you cannot speak Mandarin, it could be a plus if you want to profit from their development