Nothing in creation exists forever. Earth had a beginning, and will have an end. Whether when the Sun enters its red-giant phases and the Earth literally resides within a star (being broiled,) or when Andromeda galaxy and Milky Way 'merge,') or as soon as 2029 or 2036 when a great big honking rock called Apophis gets here.
Ever organism eventually dies. Ever star exhausts its fuel and goes dark and cold. And over a trillion years hence, the universe itself will have made the last star, the last star will die, and the universe on the whole will be dark and near Absolute Zero for the rest of time. Universe may not be lifeless then, but whatever survives will be unlike anything we can imagine at this point.