20-Year Prospect
You can bet your bottom dollar that people will always need a place to put their bottoms, and furniture reigns supreme for that sort of thing. From functional to funky to downright impractical, furniture will always be important. Someone has to make all that stuff. The only question is who, where, and out of what.
Sorry, that was three questions.
Technology is advancing by leaps and bounds these days, and we might soon find ourselves using 3D printers to make our chairs and beds. Then again, maybe not. Plastic just isn't as classy as wood, and that's not likely to change no matter how advanced those printers get. Humans like luxury, and nothing says luxury like beautiful, expensive furniture.
Up until just fifteen years ago, the U.S. built plenty of furniture (source). But then, overseas competition heated up, and their prices were so low that many U.S. manufacturers switched to importing much of their furniture and selling it, or having the pieces manufactured abroad and then upholstering them in the States. When will the madness end?
Actually...probably within the next twenty years. While the cycle of import/export will never go away, furniture manufacturing is starting to pick up again in the States (source). Quality and individuality are more heavily sought after and American buyers are starting to look local again. That's good for you since it means this job will likely be around for many years to come. Sit back, relax, and hope the trend never reverses.