What will happen to the Earth? We tend to worry about issues like climate change that can have an impact over periods of time comparable to an average human lifetime.
For the Earth, however, the biggest changes generally happen over hundreds of millions or billions of years. Supercontinents come and go, mass extinctions wipe out almost all life, and changes in the surrounding Solar System have an impact.
It is ultimately the Sun that will decide Earth’s fate. Billions of years from now, as our aging star begins to runs out of hydrogen fuel, it will change into a red giant and expand out into the inner Solar System as far out as the Earth’s orbit.