Well isn't this a lovely thought? Apparently, a new study released in Nature shows that Earth and Venus could possibly smash into one another in the future due something called orbital chaos.
Orbital chaos can cause a solar system to go crazy and send planets crashing into one another. Of course, this isn't even possible for another 3.5 billion years or so. And even then it might not happen.
The solar system is expected to last another 5 billion years, at which time the sun will become a red giant and absorb all the plants nearby. After scientists ran several simulations on a computer to see how the planets' orbits will look in billions of years, they noticed that in several cases, Mercury becomes destabilized (due to its already uneven orbit), sending it spinning out of control and causing the rest of the planets to collide and generally destruct.