Big Freeze

Big Freeze is one of the possible scenarios for the destruction of an universe. This only happens in the universes with open-ended topologies that aren't curved in a 4-dimensional multiverse.

Much time later, the expansion seems to neither accelerate or decelerate, as the universe keeps expanding at a steady rate. Eventually, the temperature goes down as the density of the concentration of galaxies also goes down. At the temperature close to zero, things dissolve into subatomic particles.

This is only the scenario which doesn't lead to new gravitational singularities.