It is not known how the universe will end, or even IF it will end. The universe is constantly changing and will continue to change for an infinite amount of time. There are galaxies that are constantly colliding with each other, creating new galaxies, new stars, and new planets.
There are black holes which also constantly change the landscape of the universe. Some even believe our universe began from the black hole of another universe, and perhaps our universe will end the same way. The universe also bends time and space so that what we think is the end may be just the beginning.