Some people are reporting that the ZL and ZR shoulder buttons might be analog-based (kinda like what the GC controller has).
As far as this whole business of Nintendo shooting themselves in the foot because they didn't add it at launch, there is more to it than people think. For one, Nintendo doesn't make everything for their devices. What they don't make, they purchase from other companies in bulk. With this, Nintendo designs their devices around the components they purchase with the components they make themselves. The 2nd slider pad, as people continually say, could have been placed on the lower-right corner, below the face buttons. The fact that there is no available depth inside the unit for it makes people think they might as well made the handheld bigger to accommodate that. So what if they did, and how much bigger? The overall handheld would be bigger, but because many components, such as the screen, are not made by Nintendo, those won't change in size unless those companies had originally designed them bigger for mass production (since such manufacturing is based on the assembly-line system). For something like the screens, bigger usually means it costs more. So, either the handheld would be bigger with components staying the same size, or everything is expanded which would raise the cost of the device as a whole.