There are a host of reasons why he'll never be POTUS; his Catholicism is not one of them.
For whatever reason, it is almost impossible for a Roman Catholic to become POTUS. That is why there has only been one in our history....JFK.
There is a large part of the electorate, especially in the South, who would never vote for a Catholic, period.
Agreed that the prejudice against Catholics is much less than previously in the population as a whole, there are core groups necessary to win an election, the Scots-Irish, for example, who would never for vote for a Catholic.
Read James Webb’s excellent book, “Born Fighting: The History of The Scots Irish in America “. He traces it back to ancient Rome, and it persists today.