The efforts by the GOP to repeal Obamacare, and the threats to stop insurance subsidies to help cover the cost of insuring working and middle class people, have already had a negative effect on the percentage of uninsured Americans. Because of that insecurity about what will happen, insurance companies have raised premiums. That is causing some to be unable to afford insurance -- the the percentage of uninsured Americans has risen from 10.9% to 12.3%. That may not sound like much, but remember that each percentage point represents about 3 million people.
Now that Trump has stopped those insurance subsidies, and it is unsure what Congress will do about that, we can expect the number of uninsured to continue to rise. Trump is gloating over damaging Obamacare -- and that shows he really doesn't care about making insurance unaffordable for millions of Americans. He only cares about the rich (who don't need Obamacare).
The chart above is from the Gallup Poll, and it was done in the third quarter of this year (July-August-September) of a random national sample of 45,743 adults, with a 1 point margin of error.