The Constitution is a social contract whereas the people as individuals have consented to surrender some of our freedoms to a national authority in exchange for protection of our remaining rights.
If the government can no longer or refuses to protect the people it has defaulted on this contract thus making it null and void. Refusal to appropriate funds for the government to effectively operate effectively and immediately terminates this Constitution and its contractual obligations.
The House passed and sent a budget to the Senate. If the Senate fails to approve appropriations due to Obamacare, then the Union is over. October 11th, 2013 12:01am EST., The 50 states shall become 50 nation-states. No succession needed.