That's utter nonsense. First off, there probably aren't 10 million Muslims in this country- the numbers are greatly exagerated by groups like CAIR. Furthermore, a large percentage of Muslims in the US are associated with the Nation of Islam, which isn't really Islamic and has no terrorist ties.
Even if there were 10 million muslims, about half of that number are women and of the five million men, half or more are going to be too young or too old to take part in any insurgency. Assuming every Muslim male (including the NOI) between the ages of 15-50 took up arms in some type of revolution, we'd be looking at 3 million, tops. Even if the police and military couldn't put down a revolt like that, do you think that gun-owning Americans wouldn't be able to stop it?
There is no possibility in the real world that Muslims will conquer the US.
Was the DC sniper a genuine Muslim or an NOI member?