Politically, the big unknown is whether or not Paul Ryan and Mitch McConnell will get away with trying to pin the blame for this on the Democrats/the law itself. That's why they've been pushing the "Obamacare is already in a death spiral!" claim hard for the past few weeks, even though it quite simply isn't.
...So, if this does end up in a worst-case scenario, Trump's "stop enforcing the mandate altogether!" order here could end up causing that death spiral even if the GOP doesn't technically end up repealing anything legislatively. The carriers would start announcing that they're bailing next year as soon as this spring (remember, the first paperwork for 2018 exchange participation has to be filed in April or May), and McConnell/Ryan would simply say, "See?? We told you it was collapsing all by itself! We didn't touch nuthin'!!"
U.S. health insurers Aetna Inc and Anthem Inc on Friday sought to reassure investors that their Obamacare businesses had not worsened after UnitedHealth Group Inc warned of mounting losses in that sector.
Aetna and Anthem said their individual insurance businesses, which include the plans created by President Barack Obama's national healthcare reform law, had performed in line with projections through October. Both backed their earnings forecasts for 2015.