Simple math shows the number of radical, terroristic attacks will increase. Yet I still feel pretty safe that if they tried to force sharia law here, they would get put in their place, and put in place in an expedited manner. Even if our military somehow just mysteriously disappeared, our little homegrown three percenters would find their numbers much higher than 3%
Aside from our oath keepers who would stand and fight for their convictions, think about all the inner city thug life gang bangers. It would be interesting to watch radical Islam try to convert your typical 107 Hoover Crips or MS-13. Strange world, If southern US militia/guerilla fighters fought side by side with the cartels. Yeah I don't think the cartels would just role over and convert, like us they are not going to give up their way of life and livelihood, at least not without a fight. A war on American soil would be just as complex with multiple factions all fighting each other, see Syria's civil war.
Another thing is that the majority of Muslims over there are nothing more than dirt farmers, peasants and proud beggars. It's interesting that at the rate they are killing each other with war and famine their numbers continue to increase. I'm more concerned of a wall of Muslims pouring over Israel's border, their camels don't have to be able to swim oceans to accomplish that...