Hi Katie, I presume you mean the atmosphere of the Earth. Many changes can take place in the atmosphere depending upon things like global warming, volcanic activity etc. but it is safe to say that the gravity of the Earth is large enough that it will always be able to hold on to some kind of atmosphrer, even if it is not one that we like. At least for the next 4.5 billion years. At that point the Sun will undergo a dramtic transition as it starts to runout of hydrogen fuel to turn into helium. At this point the core of the sun will collapse ans start burning helium. In response, the outer portions of the Sun will expand to about 100,000 times its current size. This expansion result in the burning off of our atmosphere and will eventually engulf the entire earth.

David