I don't see how one can have any hope in a Semantic Web ever succeeding when we haven't even managed to get HTML tags for extremely common Internet things: pricetags, comments, units, avatars, usernames, advertisement and so on. Even things like pagination are generally just a bunch of links, not any kind of semantic thing holding multiple documents together (<link rel> exists, but I haven't seen browsers doing anything with it). Take your average website and look at all the <div>s and <span>s and there is a whole lot more low hanging fruit one could turn semantic, but there seems little interest in even trying to.