If Judge Vinson's ObamaCare ruling is struck down, what limits on government power would remain?

If the government can do anything it wants wing of the Panel of the Purportedly Superior Lawyers ropes in Kennedy and strikes down Judge Vinson's dead on ruling that ObamaCare is unconstitutional in its entirety, what limits on government power would remain as a practical matter? Government mandates a citizen buy something as a condition of citizenship is precedent. Next up say government mandates that everybody be happy and give praise to Dear Leader Obama as a condition of citizenship. How could the Panel of Purportedly Superior Lawyers strike that down?