Well, not quite five. It's going to take less than one billion years for the constantly rising temperatures to kill the vast majority of life on earth, and within two billion years the water will be permanently vapourised.
While we may hang on by living very deep underground and somehow coming up with an alternative to water (or simply keeping our existing stocks recycled down there), there's no way we'll reach anywhere near five billion years — nor will the planet as we know it.
The only real way to survive is to simply get the hell out of here. The only complications is: will we survive long enough to develop the technology to do so? Whether it's war or premature global warming (it's
inevitably coming sooner or later), there's a lot that could take us out.
