I think post 4 hits the nail on the head. If we consider religion as a sociological construct, a thing created to serve human needs, then it will probably exist as long as those needs exist. My suspicion is that religion has been around as long as humans possessed the mental ability to ponder abstractions and seek explanations for the phenomena they encountered. If they could explain phenomena they could hope to control it. I think some form of religious belief will always be around.

Religion is an extremely individualistic and personal thing.  So, depending upon who you talk to, you will get as many ideas about the origins of religion as the number of people you talk to.  Some believe that religion began when this earth's history began and some believe it has always existed and will always exist.  It seems nearly everybody has to believe in someone or something to help them in this life so I don't think religion will ever go away. 

As far as Catholicism is concerned, it's a very powerful religious force and has existed as a separate church for centuries.  It probably stemmed and grew from other religions into its present state and could evolve into yet another church or set of beliefs in the future.   

Religion as a whole will never go away.  There is no reason to think that it would.  Science can reduce belief in God, but it can never disprove God's existence and therefore will not eradicate religion completely.  As for Catholicism in particular, I doubt the "brand name" will ever go away, though it is being battered with scandal.  However, the substance of the religion may change enough to make it fairly unrecognizable.

(Please realize that this is an extremely simplified version.)Believing in powers beyond our own has always been a human trait—even cavemen could see that the sun, the moon, the seasons, etc. were larger than they were.  As civilizations became more and more complex, a sort of “story” was constructed to explain all these phenomena and give them order; usual the forces were personified, so, as in Greek religion, there are fathers, mothers, guardians, masters, etc.—the lightning, the rising of the sun, etc., was all ordered and explained in earthly terms.  In later civilizations, there began to be a human character who connected the gods’ world to ours – a son of God, part man but also godly.  These elaborations became more and more complicated, and, as civilizations took on taxonomies of their own (kings, emperors, Caesars, etc.), the persons in charge started to use the “myths” as leverages to power, so that everyone had a fear of displeasing the gods if they displeased the leader.  This is really what we mean by “religion” rather than simply “belief in a higher power.”  As for Christianity, the origin was in the Talmud and the prophecies it held (the interpretation of the New Testament by reference to the Old Testament is called exegesis).  The Roman culture embraced Christianity and, when earthly rulers wanted to rule the people, they constructed a hierarchy of the church—Popes, cardinals, archbishops, bishops, etc.  The trouble was that the rulers did not follow the religion’s moral precepts—they stole, killed, etc. in their own interests.  The Italian families twisted the Catholic Church into their own puppets, so that a pope could be “bought.”  There is much more to be said, but basically the flaw in (organized) religions  is the all too human actions underneath them.  Religions today claim their authority from “sacred” books—the Koran, the Bible, etc.—but retain the authority to interpret those books to their liking.  Will religions always exist?  Heaven knows, but history says "yes."