I have devices going back 10 years. Some of them get updates. Some of them don't. When a developer decides to stop supporting a particular OS level, you don't get updates for that app. Just because it works today doesn't mean it will work tomorrow. It all depends on the developer and the app. I have less of a concern of the OS, though, and more about the hardware specs. If that device had 3+ GB of RAM, and 32GB of onboard storage (hell, 16 would be ok with expandable storage via SDCard), and a higher resolution, I could probably live with Android 6 for a couple of years.