The general, originalist view of the Constitution follows the 10th amendment, which says powers not given to the feds by the COTUS belong to the states, correct? Which would imply that if the COTUS doesn't say states can't put term limits on Congress, and doesn't say the feds can, the power reverts to the states.
Seriously checking my understanding of the wording, and fully aware of how far away the country in general has moved away from that originalist interpretation of the Constitution. An amendment would likely be needed to pound the idea into the heads of many, but I don't think it should be.