I got let go from a job once. They lost all of their contracts within a year.
From personal experience, sometimes everything does depend on you. Whether your managers understand that or not is a different story.
Worked in a kitchen and was the only one cleaning the things that dealt with the raw chicken and keeping the cooks following health code. I quit and within the month they were put on notice from the health department and fined. Also the store manager was arrested for embezzling money from the ATM.
Oh, things will be worse for sure. The idiots won't even comprehend that it has anything to do with your no longer being there, and the "solutions" they implement will be stupid and detrimental.
The only person who really felt my departure was my manager. Nobody else had a fucking clue what I did, aside from call out their bullshit. Most of the crap I worked on either kept working, or there was years of detailed documentation about how much of a dumpster fire it was and how little I was given to fix it. I did become a few people's favorite scapegoat, though. Glad to know they cared.
I'm in the unfortunate position of being someone's boss, and I had to have a frank discussion with an employee who wanted special treatment about how replaceable they are. That conversation sucks, because if I had more autonomy, I'd grant more privileges to everyone (i.e. more WFH).
My advice: don't make yourself replaceable, your employer isn't worth it. Instead, make yourself an attractive hire, so you can always jump ship if your corp pulls something (and they will).