This is my somewhat long response to an Orthodox commenter named "John" below:
If there's any group whose future looks endangered, I would say it would have to be traditional Protestantism.
I'll grant you that the mainline denominations have shot themselves in the foot by having latched on to some of the liberal theologies that are out there. That having been said, one can still see true and good growth in Christ throughout the Protestant world.
The thing that gives me the greatest hope is, in general, the advancement in Biblical scholarship. I've been trying to look at that sort of thing, to the best of my ability, and it really does seem to me that the old liberal theologies are passing away, and that seminaries from WSC to Dallas to Covenant to Southern Baptist to RTS are really emphasizing both original languages and hermeneutics that work to combine the best of Systematic Theology, Biblical Theology, and Literary theory, along with a healthy respect for the (small-t) tradition of the church. These efforts are going to bear wonderful fruit. This is not to mention what I've seen coming out of Aberdeen.
If you have the time, take a listen, for example, to Richard Pratt's "Introduction to Pastoral Theology" messages at iTunes.rts.edu. These talk about this confluence in the best possible light. Consider that this information is not only available at Seminaries, but is available now to folks like you and me.
We understand the Scriptures far better today than we ever have -- this includes the ANE background to the OT, and how it relates, all the way through to the New Testament and early church times (the process of collecting the writings and forming a canon. For example, several writers have studied the collection of Paul's letters, and there is good evidence to suggest that this process began during Paul's lifetime.
And further, we're learning more and more about the history of the early church. There are more sources of the writings of the fathers, and more people are studying them.
Yes sure, there is a lot of growth in various parts of the world in what one might call basic Christianity, characterised by very little dogma. Christ died for our sins is about the deepest thing one might hear on a typical Sunday. Not that my aim is to denigrate these groups, but how is that a win for "Protestantism"? Its a win for minimalist Christianity, if that's what you want to promote, but Protestantism? How so?
You have cited the tremendous growth in Christianity -- it is growing tremendously fast in the southern hemisphere. I can't speak to the content of that growth. You called it "Minimalist," in that "the deepest thing one might hear is that Christ died for our sins."
Consider what Paul said to the Corinthians: "And I, when I came to you, brothers, did not come proclaiming to you the testimony of God with lofty speech or wisdom. For I decided to know nothing among you except Jesus Christ and him crucified. And I was with you in weakness and in fear and much trembling, and my speech and my message were not in plausible words of wisdom, but in demonstration of the Spirit and of power, that your faith might not rest in the wisdom of men but in the power of God."
You have to consider that this is a sufficient message. This growth is not going to get ahead of God's word. Pratt, whom I mentioned above (a professor at a mainline PCA seminary) also is part of a growing effort to use the Internet to spread good theology throughout the world. Take a look at this:
I think this is a tremendous effort, and we'll only see more of this sort of thing in the coming years.
Who has got any figures saying that traditional Presbyterians, Anglicans or Lutherans are picking up big numbers? Or is the message ABC christianity? (Anything But Catholicism) is good?
WSC is trying to foster a movement to "Recover the Reformed Confessions." Have you read any of Scott Clark's work, for example?
I believe this is a tremendously helpful effort -- the idea is to bring to mind the development of the theologies following the Reformation. Keep in mind that it was one thing to understand the need to break from Rome (especially after Rome ossified its opposition to the Gospel at Trent); it was another to form a positive statement of what Biblical Christianity should be.
Ideas have consequences, and these are good and right ideas. But they're not just fermenting around in seminaries. There is a hunger for Christ in the world. God's hand is shaping these theologies and movements, and I believe that the use of the Internet will foster the spread of these good theologies and movements far faster than the printing press was able to influence the Reformation.
You should not look backward, at the "traditional" denominations, except as they're giving form to the movements that I've described above. I'm sure we will see the influence of this sort of thing in the not-too-distant future.
As for "anything but Catholicism," I'd nuance that to say "anything but Roman Catholicism" I do believe there are things we can learn from studying the Greek fathers, but as Robert Reymond has said:
Rome’s exegesis of Matthew 16 and its historically developed claim to authoritative primacy in the Christian world simply cannot be demonstrated and sustained from Scripture itself. This claim is surely one of the great hoaxes foisted upon professing Christendom, upon which false base rests the whole papal sacerdotal system.
"Robert Reymond, “A New Systematic Theology of the Christian Faith,” pg 818.
It does seem to me though, that with recent historical studies of the early papacy, that that institution won't stand in its present form. Because of this research, it seems as if Pope Ratzinger has already started to give away the store, and I'm not the only one to have noticed this:
Certainly, no one who claims allegiance to Catholic theology can simply declare the doctrine of primacy null and void, especially not if he seeks to understand the objections and evaluates with an open mind the relative weight of what can be determined historically. Nor is it possible, on the other hand, for him to regard as the only possible form and, consequently, as binding on all Christians the form this primacy has taken in the nineteenth and twentieth centuries. The symbolic gestures of Pope Paul VI and, in particular, his kneeling before the representative of the Ecumenical Patriarch [the schismatic Patriarch Athenagoras] were an attempt to express precisely this and, by such signs, to point the way out of the historical impasse.[Joseph Ratzinger, Principles of Catholic Theology (San Francisco, CA: Ignatius Press, 1987), p. 198]