The other factor is that the conceptual space between phones and laptops has shrunk. iPhones have gotten a lot bigger, and MacBooks have gotten thinner and lighter. With bigger iPhones and super-thin MacBooks, the iPad stands out less. That trend isn’t going to reverse. And let’s put iPad sales in context: they’re shrinking, they’re less than one-fifth those of the iPhone, but they’re still 2.5 times the unit sales of the Mac.
I’ve nothing to add to his analysis of what’s happened, but I will say this: I hope that mobile computing in general is not the future of computing. While I’m sure there are exceptions, mobile devices are not productive devices. People actually making things (rather than just consuming them) are far better off on desktop machines with big screens than they will ever be on a tablet or smartphone, and that’s what I want to see more of. Mobile devices, either tablets or phones, certainly have their place, but we’ve overshot dramatically. (In a related update I’ve been tracking my phone usage since the start of 2017 with the Quality Time app, and I’ve clocked up just shy of 2 hours per day. I gotta tell you – the odd e-mail or call aside, that’s not my productive time. In fact calls aren’t really counted, as the screen is generally off during them, nor are most other uses I’m actually happy to hold on to (eg podcasts/audiobooks) for the same reason. What’s worse, I don’t really regard it as my leisure time either – it’s not something I really love doing, it’s just a habit. And underlining that point perfectly, my top used app, head and shoulders above all the rest? Reddit)