"This order doesn't even impact unsubsidized premiums directly at all. He is threatening to end subsidies paid to insurance companies to help them comply with their obligation to reduce your out-of-pocket costs.
Insurance companies are required by law to reduce the deductibles and coinsurance payments for low income people (essentially anyone who is eligible for reduced premiums is also eligible for reduced cost sharing). They are still required to do so, even if they do not receive the subsidies Trump is threatening to cut off.
You will still receive the individual ACA subsidy. You will still get the cost sharing reduction on deductibles and coinsurance. Just like you don't pay $1202 now, you won't pay the $1330 in 2018. Your premium subsidies are safe (for now). Your reduced out-of-pocket cap and reduced coinsurance and deductibles are safe (for now).
The indirect impact, though, is that the insurance company can't create money out of thin air. Because it is obligated by law to give you a break, it has to find that money somewhere. The only option is to increase premiums (or leave the market). Many insurance companies increased their rates in anticipation that Trump would carry out his threat, so because of how late he issued the order, there is not likely to be much additional impact this year.
Hope that helps. None of the articles I've run across are explaining it clearly."