One little bit of outcry at a time. Wait for the new normal to settle in and things to quieten down, then take another bite.
There are still quite a few non-federal agencies and US companies using non-US-made drones. If they bring out the retrospective ban hammer before they have a viable US-made, or at least whitelisted foreign-made, alternative, there might be a bit too much outcry. Especially so where there are life safety implications, like emergency services being impacted.
If they're going to use that approach, then I'd expect them to start coming for models almost exclusively used in the consumer space first, while continuing to put pressure on those companies and agencies that still use them. They're already naming and shaming; expect tactics like that to ramp up. Over time, products will either be discontinued by the manufacturer in favour of the next model or, if they continue to make it specifically for the US market, they can consider the impact of a model-specific ban because reasons. Once the expected level of outcry is within acceptable levels, then down comes the hammer.