iOS devices’ longevity is astonishing, especially 64-bit devices onwards. As I mentioned in the comment you quoted, increased battery capacity can only extend longevity going forward, even if runtime suffers as a result of iOS updates.I’m still very meticulous in the care of my devices, gadgets, etc though gotten better at accepting they are tools and as such will have some wear and tear.
My current, relevant examples of longevity:
I’m still using an iPhone X (circa Nov. 2017). The battery is at ~76% health (fell below 80% only after 1000 cycles, double the expected). Nonetheless, it lasts all day without concern — my screen on time averages one to three hours. I also still regularly use a sixth generation iPad (purchased Jan. 2018).
I am waiting to see what the eleventh generation iPad features and if Apple returns to more of a “budget” price, however, will probably be enticed by the iPhone 15.
Five to ten years is almost always my upgrade cycle (tech or otherwise). And I will tell you, when you wait the long/pass on several product generations, the replacement truly feels like a upgrade.
The result of larger batteries is very positive. The iPad 2 has a massive battery, but even smaller batteries fare well on iPads with a similar amount of iOS updates on them. My 9.7-inch iPad Pro, like I mentioned earlier, was forced from iOS 9 into iOS 12, which brought about a decrease from 13-14 hours to 10-11 hours. Nonetheless, battery life has remained surprisingly stable: the iPad was forced back in September 2019. Runtime today is the same as it was back then, on the same iOS version (it still runs iOS 12 today). Like with your iPad 2, I have no reason to believe it will be materially affected by further degradation: sheer battery size precludes that.I have no complaints about my iPad 2 runtime (i.e., battery capacity). FYI, in December 2020 it was at 1285 cycles — I haven’t checked it since.
The performance on the other hand… It’s laggy, games crash frequently enough, and Web surfing is practically impossible, almost every page crashes and reloads constantly. However, indeed, it is on the last supported OS, iOS 9.3.5.
Performance is infinitely better too: while, like you said, 32-bit devices were obliterated, 64-bit devices are a lot better, even updated. I have mentioned that the iPhone 6s on iOS 13 is a lot worse than one on iOS 10, but let me be clear: it’s a far cry from the 32-bit days, and it is certainly usable.
Combine that, and the 13 Pro Max is definitely a candidate for great longevity: the A15 is even better prepared to withstand increased iOS power requirements, and sheer battery size should preclude it from being affected to the point of uselessness, like it happens with iPads: they’re certainly usable even a decade later.