Summarizing the gist of previous discussions: Google won’t support an official upgrade to Android 7 with the current chipset. So the Fairphone 2 will probably stay on Android 6 until it is no longer supported (with regular security updates) and then I see two options for Fairphone:
- Upgrade the core module (seems unlikely)
- Ditch Google support for the - then anyway outdated - FP2 and only upgrade FP Open OS to Android 7 (or later?) and/or promote the by then officially supported Lineage OS port (and/or other alternative OSes).
So all in all there are no guarantees, but the fact that Lineage OS (Android 7) already runs quite well indicates that what happened to FP1 will probably not happen to the FP2 any time soon.
And about upgrade issues: I remember back in the days whenever an FP1 upgrade came out us moderators were informed beforehand and often many of us (plus a lot of other helpful community members) were online for 24+ hours straight troubleshooting thousands of issues (mostly related to Google services).
With the FP2 updates still issues occur but you don’t even really see increased activity in the forum at all.