The report says that the March timeframe, widely rumored, is simply not going to be doable, due to technical limitations. What are those limitations?
According to an eyes-on look at a prototype of the iPad 5, while the device will remain consistent in terms of screen size (9.7-inches), it will reduce the size of the device in every other dimension. In other words, the iPad 5 will be reduced in width, thickness, and height, while maintaining the screen size.
To do that, Apple will reduce the left and right bezels (in portrait mode), similar to the RAZR M. It will only have enough space above and below the screen to handle the required front-facing camera and Home button.
In order to do this, though, Apple will have to make significant internal changes. For one, the screen technology will possibly move to IGZO, which means a heavy reliance on Japan’s Sharp. You might recall how Sharp struggled to produce the iPhone 5 screens, so this might explain a move from March to October, as well.
Of course, the iPad 5 rumors and release date are pure speculation at this point. While it is true that the iPad 4 was a minimal update over the iPad 3, leading some to speculate that the main reason for the 4 was to further push the new Lightning dock connector and to hit the holiday season, it's unclear that March was ever a viable date, anyway.
As has been noted previously by analysts and others, Apple has viewed the iPad as an excellent holiday shopping item. It had long eyed moving it to later in the year, to make it more giftable, and the October ship date of the iPad 4 was an opportunity on many levels.