Image & Form are slated to bring Steamworld Dig 2 to the Nintendo Switch sometime this summer. They haven’t nailed down an official release date, but I’m willing to bet that we’ll see more closer to E3.
Steamworld Dig 2 has been described by the developers as being much more like a Metroid-vania style game with the depth of Super Metroid than the randomly procedurally generated dungeons that filled the first game. That means there’s more to find and more to do with the increased scope of the game.
The devs recently did a Q&A session where they answer a bunch of questions about the game, including some of the finer gameplay details so if you’re interested be sure and check that out.