The city-state solution is the only way - large urban areas need to be granted statehood. The Senate would be a wash, as less populated areas could be further subdivided to keep the number of new Senators roughly equal.
The union is dead. The left can have their urban,university,1% and state capital sh*tholes and call themselves autonomous sh*tholes and we should rip out all American historical property and national landmarks as possible putting them in areas where Americans can value and preserve them.