No Android 5.1 for the HTC One (M7) except for the Google Play edition
The HTC One (M7)'s updating journey will come to an end with Android 5.0. It was a long and winding road (cue violins) that took the device from Android 4.1.2, to Android 4.2.2, Android 4.3, Android 4.4.2, Android 4.4.3 and Android 5.0. The Google Play edition of the phone is expected to receive Android 5.1 early next month.
Android 5.1 contains improvements to battery life, RAM management and system stability. It also keeps a lost and stolen device locked until the rightful owner signs in with his or her Google account information, even if the handset has been factory reset. Unfortunately, HTC One (M7) owners (outside of those with the Google Play edition model) will not experience all this. Those with the HTC One (M8) have another of updates to look forward to until the two-year period expires on that model as well.
source: @moversi via AndroidAuthority