2 month ago there was a message about new mid-end HTC device which has codename M4, also there were some spy pictures of that device published by GSMArena
So here some updated details about this device:
Snapdragon 400 MSM8930 1.2 Ghz Dual-Core
Screen 4.3 inch 720p resolution
Cameras: HTC UltraPixel/1.6M
GPS/Glonass
ROM 16GB
RAM 1GB
WiFi 802.11 a/b/g/n
Bluetooth 4.0
Android 4.2.2
Sense 5.0