I really don't want to see Orlando again. That is why I'm mainly against the idea. In my opinion, Bloom isn't all that great an actor, and I agree with GB about LOTR being his best film. But LOTR was really his first big film. So he was young and inexperienced, and yet he thought he was awesome. I don't know if he has changed at all, but the thought of Bloom being Legolas again just makes me cringe.
Legolas was a great character, and the movie really dumbed him down. I understand that they had to do that, since they cannot correctly develop 20 characters. But his role was reduced to stating the obvious, offering help sometimes, and kicking ass.
But, other than my thoughts on Bloom, I am ok with the idea of the CHARACTER being in the film, but not too much. We don't want him to be too involved with the high matters of the world. He never really did that stuff until LOTR. But I guess I wouldn't mind seeing him in Mirkwood somewhere.