The problem with this idea is that a good portion of Arlington and Alexandria will become part of DC. These areas are Federal Govt workers, lawyers, NGO workers who have a lot of money and power. The first thing they would do is insist on representation in Congress (as they are currently represented in VA). IMO, this would lead to major pressure to give statehood to DC or, at the very least, more representation in Congress like Eleanor Holmes Birton. But I suspect, given the demographics, that DC would become a state pretty quickly.
Be careful what you wish for.
Wouldn’t the constitution need to be amended in order to make DC a state? IIRC, the founders wisely and clearly said the seat of federal government shouldn’t be. IIRC.