I just think people look silly when they post things that haven't been proven. For example, I was told by reps at Apple and Best Buy, that the new SE 3 definitely wasn't going to have a home button, and yet here it is. I'm not sure what the purpose of rumors is, other than to confuse people.
The iPhone 6S was rumored for *years* that it would lose support for iOS, and yet the updates kept coming. Anyone could have looked at Apple's software history and determined they usually provide updates for 7 years on Apple devices. That's why I believe the iPhone 6S will not support iOS 16, and why iOS 15 was probably the last update for iPad Air 2.
However, the 6S is not that different from the 7 and 8 (same 2GB RAM and 64 bit which 6 does not have), so it's possible that it will in fact support iOS 16. I think a lot of it comes down to how much market share these devices hold, and if Apple wants to leave so many people using unpatched devices. I believe the iPad Air 2 is still very widely used and why it has supported 8 (!) versions of iOS/iPadOS.
The exception to this rule was the MacBook Pro MD101 which supports 9 versions of MacOS 10.7-10.15, because this model was extremely popular and was sold for 4 years after its release. I own one of these computers and it's fantastic, 10 years later.