20-Year Prospect
The future of geothermal energy looks rosy. As the world looks for alternatives to petroleum and natural gas, geothermal energy is a clean source of energy that, unlike either wind or solar, can actually provide base load power generation (source). The sun only shines and the wind only blows for part of the day, but the Earth stays hot around the clock.
There are additional reasons to bet on geothermal as well. In the past, when dry stream plants were king, geothermal had been limited to geological formations like natural reservoirs of warm water. These resources include The Geysers in California and the twenty-five active volcanoes in Iceland (source). But that was before flash and binary geothermal plants changed the game. As more efficient, closed systems, they can also make use of cooler sources of water.
Two things in particular make geothermal energy a fantastic investment for the future: first, enhanced geothermal systems (EGS) technology; and second, developing countries. Where in the past we've needed to seek out hydrothermal sources, EGS allows us to proactively inject water into subsurface fracture systems in order to basically engineer a new source (source). The U.S. and Australia have recently finished some awesome new EGS projects (source).
The future of this industry is also especially strong in Asia and the southeast Pacific areas, like Indonesia and the Philippines. The number one country with most projects under construction is Indonesia, followed by Iceland and then New Zealand (source). So hey, even if the USA suddenly stopped all geothermal energy efforts (arms crossed and nose upturned), you'll still have plenty of opportunities internationally.