Apparently, according to this article we've got less than 5 billion years.
If all else fails, the Earth will almost certainly come to an end in about 5 billion years when it falls into the expanding sun.
I'm not sure if this is supposed to comfort us by relieving us of the fact that the world will not end in our lifetime or give us hope that this despotic evil world will end eventually. Not exactly comforting either way.
Now more than ever, people are looking for answers to the intriguing questions surrounding the ultimate demise of this planet. Why now? The signs have arrived. Just as one can predict weather patterns based on observable traits, we're seeing the culmination of many events prophesied long ago.....
Fear not for when you hear of wars, rumors of wars see that you are not troubled for nation will rise against nation, kingdom against kingdom. There will be famines, pestillences, and earthquakes. All these things are the beginning of sorrows.