I spent several years of my life learning Mandarin and, although I am about ready to enter a Masters program so that I will become proficient in both Japanese and Classical Chinese, I strongly doubt the utility of any and all of the above for most professionals. While there is certainly a large degree of discipline and effort necessary to be fluent in these languages (I am technically fluent in both Mandarin and German, although technical fluency seems a low bar to meet) this means little all things considered.

Why? Ask yourself what you will do with the language once you have learned it. Unless you have a strong interest in classical literature or contemporary politics, both of which would essentially making the transition to an academic career, it is hard to justify the time invested in learning such a language, esp. when the best and brightest speakers of that language also speak yours and have more hours (cumulative over more than a decade) to become proficient in yours than you do for theirs.

Now, you might say, what if I go to China and attempt to make something of myself among the economic maelstrom?

Well, what exactly will you do? Have you thought that far ahead? I was there, in several cities, with part-time work as a translator among other things. My experience and the experience of close associates is that, despite frantic generation of infrastructure and cheap consumer products for sale in the United States, there simply isn't a lot going on that would qualify as "interesting," and "interesting" and "challenging" work is what I personally thrive on. Also, since you cannot be a Chinese factory worker, you will be limited to making dubious investments with generally disreputable business partners (see the China Law Blog, an excellent resource on this topic and the enforced opacity of the Chinese Legal system), or serving as a middleman for cheap consumer products. You could also try to promote human rights or green tech but, frankly, why do you need to go overseas to do that? There are lots of opportunities in the US to promote environmental consciousness or reduce sex slavery.

Moreover, from what folks who invest at a much higher level than I have access to, corruption is rampant and infects virtually every aspect of public life and the necessary shift to transparency which should accompany liberalization (e.g. open media) has not happened, meaning that corruption often increases instead of being exposed (reporters are routinely dismissed who do not tow the party line).

So learn Mandarin, sure, if you are really interested in it. I spent approximately four years of my life on it, worked as a translator, co-founded for a non-profit dedicated to China-related issues, worked in a think tank on economic policy and China. I learned a lot about how the world works and, ultimately, how poorly it all works.

Of course, it might also be an eye-opening experience as to what is happening in the United States. Another commentator on this thread remarked how trade will optimally decrease wars. Yes, it is possible to subject virtually everything to an economic motive and many policy makers in the United States seem to see complete integration of Chinese and American systems as an ideal. Decide for yourself what that means.