Steve envisioned the iPad back in the 80s, and he was there for its initial development and even for the iPad 2's launch (although by then he was pretty ill). One thing I think Steve got right - and that I kind of feel like Apple is starting to forget - is that the iPad was really designed with a specific goal in mind: to replace the netbook. It was actually first introduced at a time when netbooks were all the rage, and Steve and Co. basically looked at the things people were doing with netbooks and then tried to make a device that excelled at those tasks but was not meant to replace a computer, just as for most people a netbook was not their primary computer. Apple used to show slides showing a MacBook, an iPhone, and an iPad, in a modernish take on their "Digital Life" marketing campaign from the early 2000s.
Nowadays, everyone including Apple talks about how an iPad can "replace your laptop". Thing is, it cannot, and it should not, replace a laptop. Trying to get an iPad to do laptop (or even worse, desktop) optimized tasks just seems antithetical to Apple's typical UX-focused philosophy. Of course there are some creative apps that can hugely benefit from a touch screen, but, for example, nothing can beat the precision of a mouse pointer (not even an Apple Pencil). Typing on a nice full-sized keyboard is far more pleasing than the shrunken Smart Keyboard case. You're still limited to either the internal storage you purchased, or cloud based storage - a lot of professional tasks do involve shuttling around huge amounts of data, and not being able to use a portable SSD can be a dealbreaker (although that USB-C port will prove interesting - what happens if you plug in a flash drive?). And while iOS does have some useful creative apps on it today, the original purpose of the iPad was a content consumption device (which is what people mostly used netbooks for) - it's great for watching movies, reading websites, reading magazines and the like, but a pure touch-only environment is far from optimized for most creative tasks (other than perhaps drawing).
The whole point of all of this is, you can't say "The iPad has similar performance to a MacBook; therefore, the MacBook is now a useless product." Even the article tries to simplify it to this level by saying that the iPad is half the cost of the MacBook for the same performance. But performance is only one of many metrics that define whether a computing device will be appropriate for the intended use case, and for a lot of people, an iPad simply cannot fully replace a laptop. And that's OK.
As for ARM vs Intel, though, I'll play "conspiracy theorist" and claim that there is a fringe benefit to Apple moving to ARM - the Hackintosh community will be dead in the water. I'm sure Apple had to know this might happen when they moved to Intel, but modern Hackintosh efforts have made the process almost plug-and-play, and the commonality between PC and Mac hardware is so close now that many people don't even need any drivers or other trickery to get macOS to boot. To be fair though, I don't see ARM surpassing Intel at the high-end for a while, so I could envision a world where you have both ARM and Intel Macs out there, and since OS X has always had the multi-arch binary capability, and since we could easily see a "Rosetta 2" that can JIT-translate x86 code, the lower-end Macs may very well end up with ARM. So it would suck, but it may just become that in order to run Windows on Mac you need a MacBook Pro or iMac Pro... (Or maybe VMware would be able to utilize the JIT compiler to make a sluggish but serviceable Windows VM engine...)
