Recent reports convey that Google might be currently performing the internal testing of Android 4.4.3 through a process known as “Dogfooding” meaning the work is nor performed within the Android team but outside. It. Thus the release might come soon but there is no surety regarding the timeline of release.
The update might come with bug fixes basically for Nexus 5 that is facing the battery drain issue and will be known as the KitKat MR2. This process of Dogfooding is specifically performed to resolve the issue for Nexus devices. Moto X and GPe devices are soon to get the update for a few days from now. It may take few weeks ahead from now to get the OTA update. However, Nexus 5 would soon get the update. This update is basically for fixes and there is no word regarding any of its new features yet.