Are you installing a TV over the mantle?

If you have room, I would add a low media type console to put in front of the alcove to hold your cable box/etc. Can you post a picture further away?

we have a lot of our mess in a large covered basket. choose an open-ish weave one so heat doesnt build up. you can easily cut holes in the sides or back for cords to go in and out.

you could find one that fits right inside your niche.

second choice, a small end table or night stand that fits inside the niche. something can be on top, remotes can be stored in a drawer, cut a hole in the back for the cords to curl up inside a cabinet door.

Picture of the whole wall with fireplace. You'll want something that balances with whatever is on the other side.

I would add a cabinet in front or just have shelves built with doors added , attach a infrared receiver. Maybe make the doors flat panels that look like staked firewood.

Is there a way to just make the niche taller and do a built in? https://www.amazon.com/Infrared-Resources-External-Universal-Receiver/dp/B0107LT77S/ref=lp_3031544011_1_1/139-1349963-8040453?srs=3031544011&ie=UTF8&qid=1508789192&sr=8-1

Do you have pets? You could do a custom pet bed or cushion in that spot. In this room, two small dog crates plus some unattractive cabling are covered by a custom curtain hung on a tension rod to the right of the fireplace/TV.

One or two doors with rattan

uh-oh...