Yes, but when that happens you can just drill deeper. But of course, there lies the crux of geothermal power and why it isn't really taking off. In most parts of the world, that drilling part is just too expensive to pay off. Would be really neat if we could drill cheaper though, it's a stable and near limitless energy source that is available everywhere. When the economics improve I'm sure it'll take off as an energy source, but when that might happen is anyone's guess.