It's not as simple as people getting accustomed to pay 100$ for a game. There are big differences between working for 5 years on a project and then trying to make a profit from it by selling it at 100$, or go bust (because after 5 years, it's one or the other), or releasing it à la PDS, after a couple of years with an average or below-average price and, subsequently, frequent DLCs that build on it: that mirrors more closely the financial needs of studios. They take an assumable risk initially (PDS wouldn't have gone bankrupt if Stellaris had sold poorly; it's a project done with a reasonable amount of time and effort), use that money to develop the first DLC, then use that money to develop the second one, etc etc. It's pretty ideal from their point of view, it's a safe and gradual source of income. They're getting a constant amount of money safely over a prolonged time, instead of taking a huge risk.
I think we'll be stuck with the DLC model for a long time. It just makes all the sense for devs.