Odds of Hanging On
Most furniture makers got into furniture making because they like making furniture. It sounds kind of obvious, but not everybody has the luxury of doing what they love for a living. Not everybody has the luxury of loving what they do for a living after they've done it for fifteen years, either. Sure, you like making Shaker-style chairs now, but will you still love it after you've made a bazillion of them? This job can get very repetitive, so be sure you find some joy in the process before you commit.
Aside from continuing to like the job, your odds of staying in this business depend a lot on how careful you are. Obviously, you've got to be careful around saws, drills, and industrial-strength glue—a bad accident could ruin your career in a heartbeat—but you've also got to be careful when measuring and assembling, otherwise your furniture could end up all rickety and uncomfortable. No one's gonna wanna sit on that stuff.
If you're the impatient type, you'll probably find yourself looking at the job listings before too long. Same goes for if you really like peace and quiet—you'll be working around plenty of power tools.
On the other hand, if you really do enjoy making furniture, and you're totally cool with taking a lo-o-ong time to make sure that everything fits ju-u-ust right, then there's no reason why you shouldn't be able to hang on to that air drill for a good long while. People will always need stuff to sit on, stuff to lie on, and stuff to hold other stuff.