The Nintendo VS Twitter account just announced that Splatoon 2 is getting the 4.1 update tomorrow.
This update adds the new Skipper Pavilion stage pictured above. The update also adds new weapons from the Toni Kensa Collection and new sub and special weapons. The highlight of the update for me is the new music tracks that will be added. The full patch notes will be available tomorrow.
Splatoon 2 is available on Nintendo Switch. I hope a future update allows us to skip the stage intro with Pearl and Marina.