Even amateur prognosticators could have seen this one coming on the day that the iPad was announced. With Apple's hardware being so pretty and so full of excellent features, the only way any e-reader competitors could ever hope to beat them was with price. That's exactly what Sony is doing with their own Reader Pocket Edition, dropping it down to just $169 from $200. Of course, since the iPad is $499 (and competitors, like the Kindle and the Nook, are in between Sony's e-reader and Apple's tablet), there is a little more room for them to play with. However, someone's got to take the low road, and it looks like Sony is going to try.
There is one more weakness that might possibly arise on Apple's side, and that is selection. Apple is rumored to be scrambling for content deals, while Amazon is trying to make sure that their Kindle program sits front and center everywhere it can. If Apple can't lock down content the way it wants to, Amazon and Barnes and Noble may still have a chance to secure an audience. That, combined with their lower price and more focused nature as an e-reader, could allow them to portion off some of the market.
It's going to be a tough road ahead for anyone trying to compete directly with the iPad, though. Pre-orders have already been big, and as the devices make their way into the real world, sales will likely get even bigger.