Within one year of the ratification of this amendment, every citizen of the United States shall be the citizen of a State.
The new design of the Senate ensures that even tiny states will not have disproportionately large representation in the Senate.
Congress would almost certainly vote to make DC a state.
The territories should probably have a referendum as to whether they want to be a state or an independent nation. Statehood should require the consent of both the territory and Congress. Otherwise, the territory should become independent.
A year should be enough time to sort this out.