VR. It seems just about ready, but still a little too expensive. While good games are obviously already there, I'm more curious about work. Would an infinite desktop with an appropriate interface beat the reliable old 2x24" screen setup I have? I think it could.
Not just for games. Imagine VR tourism, meetings... or even escapism. Especially these days. Last time I used one the graphics isn't as immersive yet. I don't mind tethering it to a powerful computer. But image quality is a must.
Interactive virtual worlds are wondrous but not actually terrible practical for traditional tasks. Something that is perfect though is training for roles involving a lot of awareness and physical interaction in rare and extreme environments e.g. emergency workers, police, soldiers etc.