So my husband and I bought a 60" flat screen and decided to mount it above our fireplace where a mirror had previously hung. Come to find out that with the age of our house, and chimney it was going to cost us almost as much as the TV itself did to have it professionally done. So we decided to build a new, much larger mantle over the existing one so that our TV, WII and DVD player had a home on the mantle as well.
We ran across several problems while designing this. 1. the next buyers may not want this huge mantle here to put their TV on and 2. because of the age of the house and lack of plug ins, how where we to hid all the cords.
The new mantle sits over the old and above it about 3". It is attached to the wall, with 3" boards attached underneath that simply sit atop the old mantle. The boards are in a serpentine fashion and not only hid the cords underneath, but also the power strip that everything plugs into. The TV not only sits on the new mantle but is also secured to the wall behind it. The front of the new mantle hides the space between and any cords. And we stained it to match the old. So unless you are very closely inspecting it, you wouldn't even know there are hidden cords or that it is not completely original.
Problem solved. If a new owner wants to revert back to the old mantle, all they need to do is remove the top, patch the holes and dust the original back to its former glory.