“Unless one says goodbye to what one loves, and unless one travels to completely new territories, one can expect merely a long wearing away of oneself and an eventual extinction.” -Jean Dubuffet
In the far future, all the galaxies within our Local Group will merge together, with enough gas and stellar material to form trillions upon trillions of new stars. But the amount of fuel is finite, and gravitational interactions are chaotic. At some point, the star forming material contained in our galaxy will come to an end, while more and more stars and stellar remnants are ejected from the galaxy. What will be left, at that point?
Just a few stellar corpses orbiting in a halo of dark matter around a central, supermassive black hole. That mass will grow larger and larger, up until a certain point. Once it’s grown all it can, Hawking radiation will result in the decay of that central black hole, unbinding the last structures of normal matter. In the end, there will be nothing left but a large, massive clump of dark matter in the abyss of empty space.