What's next for earth in the next billion years?

By that point, I am certain all life forms on the Earth will be extinct. The most probable fate of this planet is absorption by the Sun in about 6 - 7 billion years after the Sun has entered the red giant phase and expanded beyond the planet's current orbit. After consuming Mercury and Venus, and its last stop with be our little bluish-green planet. Mars will survive though, but the planet will spin out of orbit, due to the absence of the Sun's gravity.