I’ve thought about this from time to time. Although “the Hobbit” was written for a younger readership, I don’t think that would affect the design of the film production in any substantial way. Perhaps the orcs would look and behave in a slightly more comic and less terrifying way, but there is a strong streak of the comic in a lot of the orc design done by WETA for LOTR. But basically I think that even a younger audience watching the Hobbit in a cinema will have seen and enjoyed “The Lord of the Rings” trilogy, and would be disappointed if it appeared to be less gritty and realistic, and less scary (fewer decapitations, perhaps?). So I don’t think that Middle –earth would be any different, and we would be in the same Hobbiton and Rivendell. And Gollum? Fifty years younger but just as ornery – and engaging. As it is, “The Hobbit” is a much simpler and more linear piece of story-telling, but the movie could be made more multi-faceted by introducing more back-story – more about Gandalf and Gollum, more about the history of the dwarves and elves, and possibly more of a build up to the Battle of the Five Armies. I think it is more of a “when” than an “if”, but really, your guess is as good as mine!