For all intents and purposes; 'No Christians/No Christianity (while it may 'be'; it may not be; so to speak). And given the times we live in; we can never say never; but I pray. . .that it is never the case.
Sure, I understand what you're talking about there. From what God says in the Bible, however, He always has a remnant, no matter what.
There were those, described in the Bible, who thought they were the only one left (or maybe just a few). God set them straight, too... and let them know that God knows where they are and He always has a remnant. :-)
You may not see a true Christian church on every other corner, or any church at all, but Christianity is not "in a church" -- it's in a person, so it doesn't matter if there is a church or not, because the actual "church" are the people themselves, who are Christians -- not an organization, not a structure, not even a preacher (or an evangelist) or a building or anything like that.
Christianity will always be around and will never disappear.
There will come a time (which I think we're moving quickly towards right now) in which people will wonder if there is Christianity any more and if it is going to disappear. That's just a viewpoint from the human side of things, not God's side of things, though.
Am cocerned and fear the 'power' inherent in these demographics - the hand that rocks the cradle, rules the world - and we have fewer hands and cradles. . .