This is a great thread -- thanks to everyone who took time to post.
I think an important takeaway I'm seeing is that regardless of practice setup you are always beholden to the bottom line of revenue. Other factors help, especially a cozy relationship between your group and hospital leadership, but you're never totally safe. Best you can do as an individual is work with partners you can trust, understand the flow of money, and strive for the flattest leadership structure possible. But even then you may get screwed.
My past gig was a group that had been acquired by a hospital physician practice group (formerly private) at a tertiary academic center. Good group, seemingly stable arrangement, hospital liked our group and we were involved and friendly with them. Then the hospital decided to sell. New owners didn't like the subsidies. We realized our group was getting shopped around (AMCs, medical schools). Then they ghosted us for over a year after our individual contracts were up. Much like the other poster above, hospital responsibilities increased in the interim because we had 6 month clause and no leverage. It wasn't pleasant, but it's another example of how our specialty is viewed by admin.