President Trump shows his cunningness. Looks like we can add master manipulator to the list of his proficiencies.
Why is he threatening it? Why hasn’t he already done it?
If he's trying to be cunning then he's misreading his opposition. Why should the Democrats give in to the threat? If Trump cuts subsidies then the tens of thousands of weeping people who formerly had healthcare but now do not will be blamed on him.
There is no incentive for the Democrats to participate. Having suffered from passing their own healthcare train wreck under Obama, the Democrats will be perfectly satisfied to sit back and watch the Republicans implement a train wreck of their own. Regardless of what happens, healthcare now belongs to the GOP.