Another devout-Muslim terror attack would boost the GOP for a couple years, tops.
Beyond that, demographics will trump bloodshed, with a shrinking white electorate giving us solid Democrat rule for decades.
The first thing that will happen is the deployment of troops to protect Mosques from Americans, the President will appeal for calm and tell us this is not about Islam. Has nothing to do with Islam, Muslims are peaceful people.
Muslims globally will be celebrating of course.
The media will set aside a lot of coverage time to talk about anti-Muslims attacks and rumors of them. They will spend time talking about white domestic terrorists too.