Remember that it's entirely possible you've seen quite a few more HDR photos than you realize, because sometimes it's used in a more restrained or realistic manner. HDR doesn't automatically equal the full-blown art look...that happens to be a very popular style right now, and may remain so for some who like it, or it may fade a bit. But HDR as a technique in some form or another is likely to be used for a long time to come as just another tool to achieving a greater capture of dynamic range in a shot.