I'm 36 and making dev. I've even started a business for it recently. A friend of mine is 60+, but still writing code for both profession and for hobby. Of course, if you want to make some progress in your career and get paid more, you'll propably have to quit coding and become a project manager or some kind of tech. manager to draw the big lines. But as long as you can still learn to use the newest technology and tricks, there is no reason to give up coding. :)