I think the stats that people cite here are astonishing.
The iPad does seem to be replacing the MacBook and other laptop brands as an everyday internet/reading/communication device.
Here's a little shift in topic, and may even be worth a separate thread:
What will also be interesting to watch going forward is whether compact tablet computers are beginning to replace smartphones. I now have an iPhone 5, and I'm about to purchase an iPad mini. My wife's old, pre-smartphone cellphone has just died on her, and I'm going to transfer the iPhone to her, then use the iPad mini as my primary communication device.
I've been considering this arrangement for several months, and I have come to conclusion that cellular phone networks are decreasingly necessary. Wifi alone, with occasional augmentation from a cellular data network, provides just as much coverage for communications. You have a large number of free-to-use VOIP and text apps available on iPad and android.
If you have the cash to pay for the iPad outright, it is by far a cheaper option. The monthly bill for data-only cellular is far lower than a standard cellular account, and the single-device wifi account will run about $5-10 per month. Makes more sense than signing a contract for a second iPhone.
If I were in the cellular network business, I'd be worried because of the iPad.