I remember in ab out 1979 (or was it 1980) when the pope visited Chicago -- folks came to our church who had never come before. Since our neighborhood was about 90% Roman Catholic, the few protestants wanted to "register their religious fervency" as well. Most never came back, though we tried to visit them.
Of course this will also increase Catholic pride for a time.
A number of people are thinking that this pope might be the false prophet mentioned in Revelation; rumors are that he is going to push for a one-world government and one-world religion. Whatever his intent, I think many of us believe he is taking the Roman Catholic Church even FURTHER away from Biblical faith, from which many of us would think it is already pretty distant. With universalist leanings and concessions toward the LGBT community, he is certainly taking his group in a different direction.
So, what impact will his visit have on those who designate themselves "evangelical" in the Wheaton/Christianity Today sense of the word (not necessarily Conservative Evangelicals or Fundamentalists)?