There have been suggestions that the value of the gravitational constant G becomes smaller when considered over very large time period (in billions of years) in the future. If that happens, for our earth,

We know that gravitational force between the earth and the sun is given by

Where

G = Gravitational constant

M_e and M_s are mass of earth and sun respectively

Due to this force the earth revolves around the sun in circular orbits.

If the value of G decreases with time and the gravitational force between sun and earth starts decreasing and the trajectory of earth will change and hence not going around in strictly closed orbits.

As the gravitational pull of sun becomes weaker the radius of revolution of earth will gradually increase over time and after sufficiently long time, we will leave the solar system