I recently had a need at work for an iPad. I received a response from IT to make sure I was aware an iPad is not a laptop and could not replace my laptop. I agree, I could not get by without my laptop (although it is not a PC but a MacBook).
I see how some consumers who surf the web, read books, watch movies, etc., could have everything they need with an iPad and no longer any need for DELL products. But there seems to be a business base that will need PCs/laptops for a while yet.