I don't disagree with you about the fate of general purpose computing, but I doubt the iPad Pro is the future. I think pfranz[1] makes a good point about laptops, but that doesn't mean that laptop has to be a Mac. Given the change in name for Apple Books, I get the feeling that an iOS, ARM-powered laptop called the iBook is that future.

1) https://news.ycombinator.com/item?id=17313710