I don't understand the author's connection between Safari being crashy on iOS 8 and an assault on the Mobile Web. For years mobile Safari has been absolutely rock solid, and iOS 9 is supposed to be a feature-light release focusing on under the hood technical improvements. It's absolutely true that mobile Safari was buggy as fuck for this iteration of the OS, but to me (and the general techosphere as far as I can tell) that's been an anomaly. I have the same phone and it swaps to landscape effortlessly with more tabs open than I can bring myself to sit through closing. This kind of stuff just happens in development sometimes.
The stuff about Facebook Instant and Apple News is actually salient to his point. Unfortunately for open web standards, speed matters and people vote with their attention, which materially drops off a lot quicker than most would guess in the aggregate. I don't think the open web is going anywhere at all but people simply prefer native apps in many cases. Not only are they more performant, but their narrower and simplified UX is a boon for many types of content consumers.
Especially with small mobile devices that lack a laptop's memory capacity and have to be mindful of battery usage, mobile browsers can't simply say "yes" to every open standard, -especially the ones that open up memory to web apps. Mobile devices simply don't have the headroom to forgive inefficient code compared to the laptop.