The latest pew results are interesting. There is sharp drop in mainline christianity in the US. How does this affect us non US citizens? Well it affects us quite a bit. If Catholicism lives in Rome, Protestantism lives in the US. The USA is where protestantism has its spiritual home. You can walk into a christian bookstore anywhere and you will find that much of the writing and music and video content there comes from the US, because the US is where the most money is spent on producing and promoting Christianity. Christianity requires a large contingent of scholars to prop it up because ultimately such an error prone belief system will come under criticism. Creating the right echo chambers where apologetics works takes a lot of money and hard work. Christians just think they win the arguments because almost everyone around them are still nodding their heads in agreement.
If Christianity loses the US it is going to be hard for it to maintain its legitimacy, because the US is really its last great bastion of dominance. That's not to say that the outcome of Christianity is already determined, but it doesn't look good. If it is a trend that continues at the present rate Christianity will dip below the 50% mark within about 21 years. To put that into perspective, a religion that has been dominant for more than a thousand years will decline significantly in a quarter of a century. Even if we double that to 50 years it is still a devastating loss.
Many Christians see positive growth of Christianity in China, Russia and Africa as a good thing, but it is largely irrelevant to Christians in the English speaking world. Speaking English means that you have access to thousands of resources on different religions and atheism through the internet. The ignorance of the third world won't last forever, and this is already evident with outspoken atheist groups showing up in these places. Christianity has never had to compete with that. They are no longer missionaries who only need to overcome tribal apologetics, they now have to contend with informed opinions and this is only going to get worse as this century plays out on the stage of history.
One thing seems to be pretty sure though, and that is that even if Christianity manages to get a new influx of converts (a revival), that they won't regain their former strength. To the Christians that think the end times are near, maybe they are right. They are wrong about it being the end for all of us. It seems like it may just be the end of Christianity. All religions die eventually.