Odds of Hanging On
If you find a job in geothermal, you'll likely hang on to it (if you want). Currently, geothermal power makes up only 4% of renewable energy-based electricity consumption in the U.S. (source). It's touted as the fourth most important renewable energy resource in the U.S., meaning it comes after the big three: wind, solar, and biomass.
But don't despair. Or, despair a little bit, because if you're a granola-crunching, tree-hugging, sustainable-energy aficionado, you're still losing out to oil and gas, big time. The geothermal field is small but ever-increasing in size, and that should be good for your job prospects. If you're lucky enough to score a job in geothermal now, you'll likely have a job ten years from now.