Cool!

Maybe the two galaxies will form a binary galaxy, similar to a binary stars that orbit each other? Or perhaps they already are??

Or because the gravitational pull of the black hole at the center of the Milky Way and Andromeda (not to mention all the additional matter in our galaxy) are enormous and since their is no resistance in space like atmosphere, maybe they will speed up if they are heading towards each other? Kinda like that compounding interest thingy.