Remember that this would yet be only another facet of what we are facing. Combined with Iraq and Afghanistan depoyments I can understand the dire warnings. Picture massive violent riots in major cities at one time. What if we decide to take on Iran and North Korea soon?
Could an 'insurgency' be created in America that would destabilize this country? Certainly we are polarized enough for something bad to happen. I think there are several groups in this country that are waiting for an excuse to go postal.
Unfortunately I believe this will happen sooner than later. It's an unsettling feeling to know that they all have a common goal. Take down the USA.