Somebody with 3G on their phone may not want to pay for an iPad that also has 3G. Like you say, we'll see.
Some consumers are going to want to have every device "do it all" and will pay for overlapping functions... I'd be happy with a wifi hotspot phone and a Kindle Fire probably...
Kindle specs vs competition.. http://zapp5.staticworld.net/images...omparison_chart_use-only-this-one-5220696.jpg