That is incorrect , Jobs compared the transition from desktop/laptop PCs to tablets with the transition from trucks to cars. And made it very clear "PCs are going to be like trucks. They’re still going to be around, they’re still going to have a lot of value, but they’re going to be used by one out of X people.”
He made it very clear that PC, like trucks today are very necessary, those who need them will continue to purchase them , no car can do the duties of a truck. On MR this quote is very much misinterpreted , trucks (PCs) are not going away, just most people do not require a computer to read email, surf the web, communicate , social media etc etc.