Does it factor into your FIRE Plans?
No, I don't think it should unless somebody is already FIRE'd or within a couple years of it
The ACA is very new. It obviously needs improvement and probably will change. Don't plan your life around today's market conditions and today's implementations of the law, or even the law itself. It is all too likely to change.
Yes, healthcare law is almost certain to change in 5, 10 20 years. The best thing about the ACA in my opinion is that anyone can get insurance - not great or cheap insurance always, but basically anyone that can pay the premiums gets a catastrophic policy no matter their health status. This is a great benefit to those that are in poor health. Before the ACA some people just couldn't get health insurance.
That being said, there are structural problems with medicine today and it is hard to imagine a system in 10 years that is less expensive or one that provides better access to care. I think it will play out like social security, in order to pay for expanding benefits someone has to pay for it. This is already happening: Higher copays, narrow networks that make finding a provider more difficult, higher deductibles, more restrictive drug plans, etc. Plan for higher medical costs in the future unless there is something disruptive on the horizon that no one sees coming.
An interesting idea is to lower eligibility for medicare to 50 or 55 shifting people from private insurance to CMS, although this would probably have the unintended side effect of making doctors that take medicare much more scarce and tough to see (unless reimbursement in increased, which is can't because then the program would be impossible to fund). This would be great for FIRE because it would significantly shorten the gap between private insurance and medicare.
When you retire at 35 nobody thinks of health care, because most 35 year olds are pretty healthy, even the ones that abuse their bodies (within reason). It is that 50-to-medicare time frame that can be an absolute nightmare. This is when things can really go wrong with health, even in people that have lived a very health life.
Also I don't know many docs that restrict insurance because they are lazy or greedy. Many can not afford to sign a certain contract with an insurance company because they would lose money on it. The overhead to run a clinic or hospital is pretty huge. Insurance contracts are usually pretty terrible, hundreds of pages written by lawyers for insurance companies that are designed to shift at much liability and cost to physicians as possible. Don't underestimate the amount of friction that has been introduced into the system in terms of paperwork, per-authorization and compliance over the past decade or so.