Recent modelling indicates that the solar system will be disrupted from the Milky Way after the next 2 close encounters with the Andromeda galaxy:
http://news.nationalgeographic.com/n...s-collide.html
The Andromeda Galaxy, about 2.5 times the size of the milky way galaxy at 220,000 light year across, is heading our way at 300 kms/sec.
The modelling indicates that on the third encounter, both galaxies will merge.