I guess it really depends on how "clean" you want the fireplace area to look. You have enough room to install a "box" style mantle in between your tv and fireplace. Though, it would stick out quite a ways from the surface to have the depth to house components.
I see that you have your air conditioning vent in the ceiling, so you should most likely have attic access above the room. You cold drop cables behind the walls to the same area where your fios cable access is behind the TV (probably have to drop electrical power too.) And you could drop the other connections to the wall area behind your pantry for you components. Go to your nearest big-box hardware store and in the electronics section they usually have all kinds of good stuff to give you ideas on hiding wires (cable channels for the walls) or receptacles for power, HDMI, ethernet, and more all in one package.