Just learned that the Milky Way's galactic halo extends about halfway to Andromeda, meaning it's possible that the earliest stages of the galactic collision could already be underway.
There are some very interesting implications there - chief among them being the possibility that the void between galaxies might not be much of a void at all. It's not unthinkable that there could be island chains of little stellar clusters across the entire distance.
What a delightful thing to think about.