Most seniors are already replaceable by a bunch of juniors and a friendly scripting language, an internet search engine and now maybe with the help of copilot and chatgpt as well. Thinking you're not replaceable because you are because you know what happens when someone enters an URL and other trivia is going to turn out to be arrogance. The juniors are less replaceable for the simple fact that they are a. Cheap and b. Who else are the higher ups going to manage.