Q: And the way to prevent them from amending the present Constitution away to be something else entirely is?
A: Nothing but unwarranted confidence that they won’t.
We already have the Law we need. We only need to have the federal obey it for a change.
If 34-35 GOP-controlled legislatures will amend away the Constitution then we are already lost. The “Law we need” then doesn’t exist and will never exist in the current national configuration (and maybe not in any configuration!).