President Barack Obama has renewed his promise that if you like your health insurance plan, you can keep it - at least for another year. It's a huge relief for some, but could amount to very little change.

That's because it's not clear whether insurance companies will revive old plans they had already decided to kill as they built new policies that were compliant with Affordable Care Act rules. President Obama announced on Thursday a policy that would allow for these plans to come back, but it was not apparent immediately how that would happen.

"I most definitely would stay on my current plan," says John Certalic, a 64-year-old charity manager in New Berlin, Wisconsin who is otherwise facing a huge increase in premiums to get insurance for him and his wife for one year until his Medicare eligibility kicks in at age 65.

But he doesn't know yet if that plan will be offered to him.

Consumers will have to wait until state insurance commissioners work out what changes can be made - if they make any - and responses are just starting to flow in. Then they can call their existing carriers or insurance agents and ask about the fate of their plans.

John Eckardt, an insurance broker in Medford, New York, is already getting calls. He has dozens of clients who would breathe easier if they could keep their current plans.

The key question remains: will insurers take up the charge and offer the old plans back, or is it too late?

"I don't know how you can force an insurance company to offer a plan," says Eckardt. "I don't see how you can possibly do that."

For now, Eckardt says he's just going to keep going forward with the enrollments he was pursuing for his customers, mostly small business groups whose previous policies were discontinued. "I can't do my business with possible scenarios," he says.

Insurance choices won't be final until coverage starts on Jan. 1, so consumers have time to wait, insurance agents say. They can continue to shop for health plans, and just not make final decisions until the last minute.

Eckardt adds that he sees little hope that the carriers in his area want to offer the plans they offered before, and he doesn't see anything in Obama's announcement that compels them to.

One of his small business clients, for instance, had a very advantageous plan with zero co-pays that they would love to continue, but Eckardt thinks it unlikely the carrier will let them. "The problem is that it's too late," he says.

STATE BY STATE VARIANCE

On the other side of the country in Roseburg, Oregon, insurance broker Kelsey Wood is dreading the complications caused by this new initiative. He has dozens of people already in the process of applying for new plans - although not a single one has completed the process yet either on the health law's new online exchanges or with private insurance.

The insurance market in each state varies, and Oregon is one where not many insurance carriers were letting people keep their existing plans, as is also the case in states like California, New York and Wisconsin. In those places, people have been getting cancellation notices and are instead being offered plans that comply with the coverage mandates of the Affordable Care Act.

But in other states, like Florida, Illinois and Iowa, to name just a new, there are already many insurance carriers letting people keep their plans, and even actively recruiting them to renew. In these states, the new push from the government to let people keep their insurance isn't going to have much of an impact because it was already happening.

Of insurance agent Jesse Patton's 850 customers in Iowa, about 90 percent will likely keep their 2013 coverage, he says. Even when they qualify for subsidies, some of his clients are better off with their former plans, he says.

One example: a client family that is paying $659 a month now and would save about $50 a month with subsidies on the exchange, but their deductible would go up by about $7,000.

MOVING ON

The impact in all states could also be muted by people already having made their choices.

Wood, in Oregon, says about one-third of his clients have insurance now and don't want to leave their plans, but that 90 percent of them had found acceptable alternatives among the new selections and were going through the sign-up process.

Trying to explain this to them, "will make my life miserable," he says. (Editing by Linda Stern and Tim Dobbyn; Follow us @ReutersMoney or at http://www.reuters.com/finance/personal-finance.)