These new programs won't close any time soon. There will always be a steady stream of new blood to fill ANY open residency slot in the US.
In the short-term, they bring physician-level services at less than midlevel costs. In fact, they actually get paid by CMS per resident (something like $100,000 per resident per year or something absurd like that). It's an incredibly straightforward business decision for a CEO/hospital board to start up a residency.
The CMGs love "training" them too. Residents will work slave hours, generate RVUs, and expose themselves to the kool-aid of that specific CMG in order to get a job. After all, they have to pay off those quarter-to-half million in loans.
In the long-term, the residency expansion will continue. The top-tier medical students and high achievers will wise up quickly and not choose EM. Your average American medical student will take a lot longer to open their eyes to the reality nearly guaranteeing a continued labor pool. Especially as the denominator of medical students increases due to rapid medical school expansion as well. Now perhaps on the decade time frame, if those medical students really stop going into EM en masse, that will open the door for the international grads or physicians who would sell their soul, first child, and their own mother for an American residency spot.