Owners of HTC's latest flagship on Verizon have been patiently (and sometimes not so patiently) waiting on the promised update to Android 4.4.3 for some time now, but it looks like they'll be waiting a little longer. Even though the T-Mobile One M8 got its update today, HTC's US president Jason Mackenzie has confirmed on Twitter the OTA is currently targeted for mid-September on Verizon.
— Jason Mackenzie (@JasonBMac24) August 18, 2014
The 4.4.3 update isn't a huge one, but it will contain security fixes (including some from 4.4.4), Sense 6 optimizations, and wireless tweaks. It should have been out already, but Mackenzie says there was an issue with GPS, so the OTA has to be tweaked and re-certified by Verizon. Note that some of these security patches could make rooting more difficult, so you might want to do that before the OTA rolls out if you were planning on it.