Like ALL religions, christianity will pass into history and either evolve into something else or vanish completely. That is the way it is. The Romans , the Greeks, the Babylonians, the Egyptians...all of them have 'lost' their gods.
God is a man made construct.
Doesn't take a genius to see that, now does it? The christian god isn't special and he'll vanish one day with absolute certainty :-)