As an engineer I've had a few ideas that I have patents applications filed on (or at least have my company's patent lawyers working on) but I know they won't make it into production in the immediate future- the technology is just too impractical to make the invention actually work. However, the ideas are close enough to reality that someone may figure out how to make it work in the future, and having a patent on it protects my idea.
I suspect that's whats going on in some of these cases.
