The ACA demands that all Americans get coverage. Since there are going to be millions more insurance customers, there is going to be a larger demand and market for health care. That likely means HMOs will grow in size. Future tweaks to the law might reverse that, but not at first.
I think that coverage for HMO's will expand with the Affordable Care Act, and I don't think that's a bad thing. I've been part of one of the original HMO's (Kaiser Permanente) for 20 years. And I can safely say that I've always received great service for them. It's an excellent model for health care.
I think it will expand just because its going to be more prominent. The affordable care act is something that is going to put the people back in charge of their health care. I can't see how it wouldn't expand the HMO health care coverage. I guess only time will tell.
I think HMO coverage will expand under Obama Care. The thing is is that more people will now have health care. Tens of millions more. And it will still be private, just funded partially by tax cuts, tax increases (for some), and government subsidies. So it will have to expand.
Now that the public has a choice, those who can afford insurance because of the subsidies being offered are now able to choose between an HMO and a PPO. The latter offers more of a choice of doctors and does not require getting the approval of a primary care physician first, which is more desirable.