It should be something original that reflects the current state of America. It should include:
* You're racist if you disagree with anyone of another race for any reason
* Being entitled to things you didn't earn or taking it from someone else
* There's no right or wrong, just whatever you choose to believe
* War of any kind is bad and people should be nice
* America should never have been founded because it's the cause of all the world's problems
* Immigration laws and dominant culture are racist
* Don't mention God or Christianity anywhere because it's offensive (but Islam is okay)
* Government healthcare is the greatest invention since the printing press
* The rich are evil, along with corporations
* Marry whoever and identify as whatever you want; biology has no business telling you what you are
That kind of anthem will ensure that everyone is happy and no one has to feel too proud of their country.