Do you think functional programming will mature enough and hit the main stream? There are some practical functional languages now that are pretty nifty, like Scala.
(If you are good with and like Java, then I recommend you at least look at Scala. It compile into .class files, and can use java libraries, but it is a functional and object oriented hybrid language, and it is really nifty. And naturally, the "official" implementation is open source. IDE support is currently a little iffy, sadly.)