"Keep in mind that this list is unofficial and Google has yet to formally unveil an Android 4.3 build. With that said, this list seems fairly accurate at first blush; newer, more popular models getting the latest release while others stay back."
http://www.androidguys.com/2013/05/30/list-of-htc-devices-slated-to-receive-android-4-3-arrives-before-version-is-even-announced/