Small interview with Sean Murray
Here is a interview stating that NMS updates will keep coming for a while, and they are working on a new game behind the scenes. I will admit I am surprised that they haven't put out any paid content, or maybe I am not far enough in the game to have seen store purchasable items yet.
But coming to the Switch soon should provide them with some extra income.
Don't think they have in game purchases for the game, although I could be wrong as I never looked.