Android 4.4.3 update might be actually coming sooner than you can imagine. How about today itself? If the US operator T-Mobile can be believed Google Nexus devices – the Nexus 5 (2013) and Nexus 7 (2013) devices might receive the update today itself.
The T-mobile website shows that the Android 4.4.3, build version KTU84M will be just an incremental update, not filled up with many new features other than security enhancements and bug fixes. There might also be Bluetooth, data dropout, camera, power management fixes but nothing more than that.
That is all we have on Android 4.4.3 right now. Watch this space for more.