Einige DataMiner haben sich auf dem Spiel wohl wie zu Splatoon 1 Zeiten etwas genauer umgeschaut und einige Details ueber neue Maps, Waffen und noch eine andere Ueberraschung gefunden.

Upcoming maps

Incomplete files for revamped versions of Kelp Dome and Blackbelly Skatepark have been introduced in the 1.1.1 update
There are additional maps named Line and Tunnel which are in development
Placeholder images for maps revealed in the Direct named Kawa and Pillar are present. (thanks to the people at TCRF!)
Nintendo is including testing versions of Shifty Station in the updates; however, for Splatfest the game downloads the real stage model and layout file separately. This explains why the existing files include debug and test objects.
The developers are currently testing new Salmon Run stages with internal names of Shakehouse and Threepoints. New files for these maps have been introduced in the 1.1.1 update as well. These are the last of the 4 planned stages for Salmon Run as of version 1.0.0.
Weapons

Grizzco brand weapons are in the works. A Blaster, Charger, and Brella were found in the files.
A new weapon type called the Squeezer is in development. Here is Sheldon's explanation text for the Squeezer and an alternate version of it.
You can find more about upcoming weapons on the full Splatoon 2 weapons list. (Thank you Lean for providing this service!)

Octolings

What was known as the player's gender from the original Splatoon has now been replaced by a pa...