My grandfather owns a successful company that manufactures and imports furniture from China. The business has made hima millionaire (not that that means anything in this day and age). But this is my question: when I "grow up", should I learn this business and then continue it? Does the furniture trade with China have a promising future? I always hear people talk about how we should reduce trade with China, so would a reduction of trade with China hurt the business (if it were to happen while I owned it)?

If it works now, it should work in the future. Just be aware that everything changes over time and what was done today may not be the same thing people do 20 years from now.