Android 7.0 Nougat was officially released over three weeks ago, and people instantly went insane over the lack of any factory or OTA images available for the Nexus 6 (but not so much for the Nexus 9 LTE, since they didn't sell too many). We reached out to Google, and it seems like you guys are gonna have to wait for just a few more weeks.
Some people were getting so tired of waiting that they speculated Nougat might not even come for the Nexus 6, but that is completely false. Google has let us know that the rollout for Nougat on the Nexus 6 and 9 LTE will begin in a few weeks, but there isn't an exact timetable available to share for those updates. We also still don't know why the updates are being delayed for so long, but there are probably some bugs Google feels the need to patch before an official release.
If you're tired of waiting and want to enroll for the Android N Developer Previews just to get a taste of Nougat, you may still be able to by registering here.