And in the U.S.? Probably 30 years.
The worst thing to ever happen to Islam is if the USA became Muslim. We would start to change it! We would have Gay Islamic Mosques, Women would have right to be Imans, We would screw it up so much they would be making war on us as heretics.
Parts of the upper Midwest may go muslim in time, but the Mexicans will have something to say about the rest of the country as they absorb the Southwest and neighboring regions of the former U.S. Each competing foreign interest (China taking Hawaii, parts of CA and Pacific territories; Russia grabbing Alaska) will divide the landmass.