Tim Cook told the Daily Telegraph that he only travels with his iPad Pro, iPhone and Apple Watch. As a result the PC is dead.
Whilst the PC is certainly dying - or at least changing - I have serious doubts that the iPad, in whatever size Apple sells it in, will ever be a complete replacement.
The iPad as it stands today just has too many gaps to be the only device that most people use, unless the have an entourage of fawning minions to make things happen for them. For Cook this might be true, for most of the rest of the population not so much.
That isn't to say that an iPad doesn't offer a solution which is good enough for some, possibly even most, use cases. Email, most web browsing, apps and gaming certainly fall under that umbrella. But there is enough that an iPad can't manage that tells me that most iPad users will be backing it up with a PC or Mac for those 'just in case' scenarios.
So if Tim Cook and Apple really want to push the iPad as a complete PC replacement they're really going to have to work on extending its capability, rather than just making it bigger.