I think you are exactly right and I’ve been saying this for a while. There is a $4 billion non-profit, academic healthcare system in my former neck of the woods with one of the oldest EM residencies in the nation that is functioning like a CMG. Of course they staff the handful hospitals in their system, but also 2X as many across several other unaffiliated systems and a 100-mile radius of the academic mothership. They have taken over contracts from SDGs and CMGs alike over the past 5 years. Meanwhile, the EM residency pumps out graduates that often stay in the system that is ever growing and part of the academic population health emphasis that garners even more research dollars. They are able to do this by offering employee contacts that are at least as lucrative (if not more) than what ApolloMD, USACS, et al can offer...for now. However, the real attraction is that employees can float between academics vs. community, EMS directorships, admin, etc. The department leadership is also more stable and physician friendly than the nearby alternatives, IMHO.
Interestingly, the academic system is about to merge with an even larger, $9 billion non-profit system with its own, more community-based GME programs (although their EM residency at the hub has an even larger national reputation). While this larger entity has community hospitals across 3 states that employ CMGs for their EDs, those contracts are being threatened by this mega non-profit system that is emerging and about to have $300+ million in operating income to play with and can churn out 30+ EM graduates a year.