Ok, the sun will not turn into a red giant for another 5 billion years, and our galaxy is currently in a collision with something (not a another galaxy, but I can't remember what), but it takes so long for these things to happen, that it will not even affect you. AND there is probably a massive black hole at the center of our (and most) galaxies.
The potential ends to a star is an explosion, pulsar, or black hole, so we have some options.
