re: What replacement phone are you considering or have you already chosen?
The 821 is just a souped up 820
So Jerry, you are basically saying don't buy the V20 due to the possibility of no Android O?
That sucks big time. I was suggesting the V20 as a replacement for a friend's Note 7. She said no way already, but would probably cuss me out if there was no update next year.
Yes. The 821 is just a souped up 820. But one of the areas it was souped in (a faster-running GPU that is the same base version) happens to have made a significant difference, especially with Android 7 and in future versions. It makes a dramatic difference in the way Nougat runs, too, because of so much dependency on the GPU in recent versions of Android, but the 820 still runs Nougat well.
Android 7 requires Open GL ES 3.1+Android extensions or Vulkan to render the UI. The Snapdragon 820 supports these. It does not support any newer graphics APIs. I believe it could, but any support for anything further has to come from Qualcomm.
If the next version of Android requires Open GL ES 3.2 (a safe bet since it's been stable and in use since June of this year) The Snapdragon 820 will not meet the minimum requirements. Qualcomm has always "forgotten" capable chips rather than update them. They no longer manufacture the 820, so they waste no resources on it. If you need Open GL ES 3.2 for your project, you buy a Snapdragon 821 which will be supported. That's fine unless you want to revisit older products and update their software.
If Google gets Android O out the door before the two-year support window for the Nexus 6P is over, they will expect Qualcomm to deliver the software required to support it on the 810 as part of the contract. If they support the 810, they'll likely support the 820. This actually happened with the 2013 Nexus 7. It shipped with Jellybean. The update to KitKat requires a higher version of Open GL than the CPU supported. Qualcomm said no. Google said yes. The back and forth continued until Google was able to force Qualcomm to honor the contract and the Nexus 7 was updated (months after the Nexus 5). We also lost Jean-Baptist Quereu, the man working for Google who was the best friend the Android community ever had over the issue, as he couldn't take that kind of stress again and went to Yahoo to be their senior developer. Thanks, Qulacomm.
Until that happens, you can't count on anything. If you want to be sure whatever you buy will run Android O, you need to buy something with at least a Qualcomm 821 if it has a Qualcomm CPU. I know Bill Yi — the fellow who took over for Mr. Quereu — will fight just as hard for it to happen if it does fall under the support window. I also know the people writing the software will try to get at least a rudimentary version of O out before the two-year period is up. But trying is not the same as being sure.
This could (and probably will one day) be solved through a software graphics API. New games run on older graphics cards on your computer because Open GL or Direct X can filter what the graphics card supports, then not use the things it doesn't support in your game. But for now, things that have a GPU dependency on mobile use direct access to the hardware, so the chip makers support is required. That's a big part of the reason the iPhone gets updated longer and runs better/smoother. Apple makes both the chip and the software. Same thing with Exynos and Galaxy S phones. They can code in support for older versions of the hardware, and make the hardware itself with the future in mind.
Google is trying something similar with the Pixel and an off-the-shelf CPU by tailoring their own Android build to a very specific set of GPU instructions for UI acceleration. But the Android team — not the Google Hardware division who makes the Pixel — still has to have more generic support and a way people like LG or Samsung or Google's hardware division can build their version to support their hardware.
This $hit's hard y'all. Most of us (me included) have no idea exactly how hard it is.