Earth is in an orbit that has been stable for over 4 billion years. There is no sign that it will not continue its predictable orbits for at least the next 5 billion years. By that time the Sun will begin to enter its red giant phase. Rather than Earth falling into the Sun, the Sun will expand out to meet Earth, and probably begin to evaporate it into a puff of silicate and iron 'smoke' by a billion years after that! A greater likelihood, however, is that Earth will be ejected from the Sun by a passing star. For four billion years we have been pretty lucky, even though there have probably been thousands of close passes by stars. In 1.5 million years the star Gleise 710 will pass within a light year of the Sun. In the 7 billion years remaining to our Sun, there will surely be many close encounters where the orbit of Pluto, or perhaps even the inner planets are disturbed by the gravitational field of a passing star.
