A new leak shows what may be the updated navigation bar for Android 4.4.3. In it, we see revamped back and recent tasks buttons, as well as a new center button, which replaces the home button in some cases. It fits an earlier leak, but the source points to this being dogfooded internally, meaning it may be set for release soon.
This image is captured with a customized navigation bar from here
, thanks Jimmy Baez, Artem Russakovskii for pointing it out!