Forget the dangerous conditions, hazardous materials, and accident prone nature of working on an oil rig. If those aren't the downfall of derrickmen, societal changes might be.
Although the world still relies on oil to a large extent, the buzzword lately is "green." Everything has turned to energy efficient as things like solar power and wind energy have become popular and viable sources of alternative energy. The focus on sustainable energy sources might be the start of a severe downward spiral for oil rig workers, who already work 14-21 consecutive days in remote areas far from home.