First of all I'd disagree, although English is currently the world's business language being multi-lingual is very practical in business. Not to mention Chinese will be more important than English soon. More importantly, there are other reasons to learn a language. Even though Spanish isn't "useful" for me in my career in any way, I'm very glad I'm more than proficient in it and can speak/write it very well. Understanding young people is really difficult though, and when they're talking amongst themselves I'm pretty lost. That I didn't do a better job learning it while I was in Argentina (I was a lazy stoner at the time) is one of my biggest regrets in life and is a reason I may return one day.
If you want to learn a language, that's cool, but as I said, there is no NEED for you to learn Spanish as you said yourself.
And just because China will become a bigger business nation doesn't mean Chinese will be the business language of the world.