Article IV of the Constitution explains the relationships among the states and the federal government.

Section 1 explains that each state must give "full faith and credit" to processes of every other state -- but then it continues to explain that Congress has the right to describe how they must do that.

Section 2 says that each citizens has the same privileges and immunities of "several states." It also describes that each state will give up any citizen of other states who flee from justice or law to another state.

Section 3 describes how to add states (and unfortunately does not say how to get RID of states).

Section 4 says that each state will have a republican form of government.

Article V explains how to amend the Constitution -- 2/3 vote in both houses of Congress or 2/3 of the legislatures of the states can propose an amendment. Then 3/4 of the state legislatures must approve the amendment.

I don't see any more amendments, ever. There's 50 states. To get an amendment to pass, 38 states would have to agree. I don't think we could get 38 state legislatures to agree that the sky is blue.