What will happen is they’ll start firing off car bombs in major U.S. cities (glad I don’t live in one) or in shopping malls (glad I don’t go to them).
Even then it will be passed off as nothing to see here folks, move along. It will have to get really bad before it gets reported on seriously.
You pose a scary ‘what if’ there. But the fact is we could send more boots on the ground and have more useless conflicts like we have had in Iraq and Afghanistan, but unless we take out the trash here at home and close the borders - its just a matter of time before your ‘what if’ does indeed happen.