7.1 sound will become the new standard
Speaker systems for your home theatre are usually your normal 5.1 setup with either Dolby or DTS that runs it all. (find out more about Dolby vs DTS here) You have your 5 surround speakers (center bar, front L+R and rear L+R with the .1 being the subwoofer for those deep "end of the world" disasters etc..)
This is great for being able to follow that transformer running across screen or that slow motion bullet passing by but that's still all based around the front to enhance the visual actions or presence on-screen if you're in that sweet spot in the middle of the square speaker setup. Now with 7.1 its a more "real" world environment with 2 extra speakers (making 7.1) at the rear sides Left + Right.
This giving you a full surround sound experience as there is much better coverage from the sides. In 7.1 that helicopter swooping round to destroy that enemy will really feel like it's not just jumping from front to the rear but thundering all the way round!
In the interest of only using my own work you will have to put up with my terrible drawing.
If you want more info then watch this DTS-HD presentation on youtube