I think most of Randy Barnett's proposed Federalism Amendments are admirable, though some would have extreme consequences which are difficult to fully fathom before the fact. But one mistake is being made repeatedly.
Article [of Amendment 7] -- [Term Limits for U.S. Senators and Representatives]This is a centralized mandate on the selection of legislators; as such, it represents not federalism but its opposite. I would propose a much milder form:
Section 1. No person who has been elected or served for a full term to the Senate two times shall be eligible for election or appointment to the Senate. No person who has been elected for a full term to the House of Representatives six times shall be eligible for election to the House of Representatives.
Section 2. ...
Many others could probably word this more precisely. [I don't know whether to say "grounds" or "criteria", and there are probably larger problems as well.] This would be more flexible and far more faithful to the spirit of federalism.
Article [of Amendment 7] -- [Constitutionality of Term Limits]
No article of this Constitution shall be construed to limit the authority of each State to restrict the eligibility of persons for election or appointment to the Senate or to the House of Representatives from that state, or to its own legislature, provided that the grounds for such restriction are limited to prior election or service in those bodies.