To quote Gary Oldman's character from The Professional: EVERYONE!!!!!
Apple wants to sell ad many iPads to as many customers as they can. They have framed it as an "8 to 80" device, and the software is basically framing it as a "lifestyle device" that supports what you do in, well, life.
Add the base software to the incredible extensibility that the hundreds of thousands of apps (that cover an incredibly wide range of needs) provides, and you have a target market of, well… All sentient creatures on Earth.
They'll be targeting other planet's user base around iPad 16 or so…