20-Year Prospect
The only danger of this job is if today's robotics engineers do too good of a job, in twenty years you'll be building robots to replace yourself. Actually, we should probably be coding that in as a precaution. "IF becoming sentient, DO NOT take creator's job. DO NOT build more robots, please. IF building robot army, THEN humans will be at your mercy. IF no mercy shown, THEN human surrender = unconditional."
Really though, you don't need to look at a chart to see that robotics engineering is set to be one of the fastest growing jobs of the next few generations. In the meantime, growth is above average, with a job increase of 29% reported in 2012 alone (source).
Another thing to think about is the incredible rate at which things progress in this business. Technologies that are experimental today may be mass-producible in ten or twenty years. If you happen to possess the twin virtues of adaptability and innovation, you should get along just fine.