@ Doug Mason:
"One billion years later, after surviving the collision of two galaxies, the Great Crowd of Other Sheep will experience the sun expand and self-destruct."
The Earth would most probably be pulled out of its orbit by the mixing of stars and their gravitational effect on each other.
The Earth however won't have to wait 5 billion years to get vaporized by the sun. Reason being that, as the sun slowly gets warmer and warmer throughout the hundred millions of years the Earth's oceans would vaporize creating a runaway greenhouse effect. This is supposed to happen a billion years from now.
The result would be no ocean, an atmosphere of water vapor that's 200 times our current pressure and temperatures over 600 degrees Fahrenheit.
The Great Crowd would have to move to Pluto.