You don't understand. The party that packs the court should have enough votes to make sure they never lose power again. If the party in power packs the court, what's going to happen is the other half of the country will just declare the federal government illegitimate and form their own.
The law has a solution for this. Portions of DC can and have been given back to the states. Frankly I think they should give the bulk of the "residential and normal city" areas of DC back to MD.