That is something that nobody knows and is almost impossible to predict. I think that when bitcoin is going to die that we are going to notice it before it actually is going to happen but right now I do not notice a thing.
Bitcoin will survive for at least two decades, and it will not die soon, as more people and businesses are entering into it which will take bitcoin to higher level.
At max it can survive a few decades. By then it will become obsolute.
I expect by then we will see a new kind of virtual currency which will take over. Something not mineable.
The only threat to bitcoin is it might get replaced by new and innovative currency in future, but till bitcoin is doing well I don't think we have to worry about anything.