Finally, several years later, we have an answer to the question shouted all over this thread, which is whether a flood of conversions to Islam will soon lead to that religion playing a more dominant role in the US.
According to Pew, for every convert, Islam loses one follower who was raised in the religion.
https://www.google.com/amp/www.pewresearch.org/fact-tank/2018/01/26/the-share-of-americans-who-leave-islam-is-offset-by-those-who-become-muslim/%3famp=1.
It would seem that immigration is the the main source of growth in America’s Muslim community, given the net wash between converts to Islam and those who leave Islam
FWIW, personally I abhor Trump’s anti-Muslim immigration policies. I’m not Muslim, either. But the numbers of immigrants were so small even before Trump that the fear-mongering seems really overblown.