[Doug Loss]

First, the supreme court can't rule a properly-ratified amendment unconstitutional. If you think that, nothing else you say is worth considering. Second, yes Congress could repeal the 17th amendment. But it won't; the feral federal government will never agree to reduce its power. The only way to get something like this done is via an Article V convention, bypassing Congress entirely.

As for "one has never met the requirements needed to compel Congress to call" an Article V convention, there have been over 400 state resolutions calling for such a convention. Since these resolutions haven't been identically worded Congress has pretended that they didn't meet the constitutional requirements, but the Constitution nowhere says that such resolutions must be identical to be valid. For that reason the Convention of States movement is working to get states to pass identical resolutions. So far, six states have done so, and the resolution is being considered by a fair number more.

[Robert DeLong]

They could challenge the procedural validity of the Amendment, especially one created via a Constitutional Convention. Which is what I was referring to. It may be a stretch but it is possible and if the Supreme Court took it up and ruled it unconstitutional then what recourse is there. Given the state of the Supreme Court, I would not put it past them either.