Google's not ready to unveil the name of the next release just yet. In the meantime, a subtle troll.
You didn't really expect Google to out the real name for Android N in a developer preview Easter egg, did you?
In any case, tap the "Android N" graphic under Settings > About phone on the latest N preview, and "Namey McNameface" appears. It's a reference back to a joke at this year's Google I/O keynote based on popular polar vessel Boaty McBoatface. Because why not?
More real, actual news from the fourth Android N dev preview over here.