There are rumours that Android 4.4.3 entered the first stage of testing. For Google, this phase is called "dogfooding" stage when the software is given to the employes for feedback and other changes before the first official release in the market.Recently, Youtube released a dogfooding update, which was very good for them, as they could receive feedback and then replace the faults immediately.
Android Police has information that Android 4.4.3 was released to almost 1% of Google employes for them to try it and hive feedback. As it just entered this first period of testing, don't expect Android 4.4.3 until a few weeks from now. It will pass some time until this phase is finished and Google will be ready to release an official version of it. We aren't expecting much changes for the new version of Android 4.
It seems that there will be some security and stability changes, but we don't have any information about other bugs that this new update may be solving like: connection dropouts or random reboots. It seems that this this update will benefit firstly for Nexus 5.
What bugs would you like the new Android 4.4 to solve? Do you have some issues with Android 4.4.2?