There you go again, comparing apples and oranges. The Affordable Care Act is not an amendment to the constitution.<quoted text>
so if one Congress re-establishes slavery, future Congresses are powerless to change that decision?
You are just being ridiculous. However, yes, Congress can repeal the Affordable Care Act but that is not what they are doing. They are attempting to circumvent a law that was passed by Congress, signed by the President and survived a Supreme Court challenge. That is not within their power. Period.