How so? Does each state have standing to contest the admission of a new state by Congress?
At the root of things, the US Constitution is a contract, between the people, the states, and the federal government.
As signatories to the contract, the states have standing to see the terms enforced.
One of the terms is that DC cannot have representation in Congress.
So, if DC does get representation, the fed has completely abrogated the Constitution.
You wanna know the funny part? I was born in DC.
Not sure if I am a US citizen.