If the supreme court ever gets to the point where one party is packing it and they're ignoring precedent, that's game over. People will be shooting each other.
Controversial Supreme Court decisions dominated much of the politics of the second half of the 20th century. At the beginning of this one, the Supreme Court picked a president. Historically, the court has been 'packed' or beholden to partisan interests several times. It's hardly 'game over'.