> It's not really clear what you do with a staff+ long-term IC
Set clear expectations in the first place. "I want to run things my way here, I'm the new management and I don't like you" is not an expectation - and that's what I have observed happen all too often.
It's not really clear what you do with a staff+ long-term IC. A lot of them don't want to manage or be involved in leadership, but they want to pull down a huge salary and just do work that is frankly replaceable by a senior eng.
To be clear I do believe there are levels of IC experience above staff, but being 21 and joining a startup doesn't make you a Principal Engineer just because you hung around until you're 30. Especially if you've only worked at that one startup.