About two weeks ago, HTC began rolling out Nougat to the HTC 10, 10 Lifestyle, and One M9 in Europe. However, the rollout for the HTC 10 was paused due to an unforeseen technical issue, with the company estimating a fix due in February.
Four days into February, the Nougat rollout has been resumed for the HTC 10. The company has also made a Nougat flashing tool available online, if users don't want to wait.
At least HTC is being open about the process, which is more than I can say for some other manufacturers. Still, with Android 7.0 passing five months old, it's not hard to see why some HTC 10 owners are becoming annoyed.