Have you tried a tv console within the 'box'? and tv at top of box... let the fireplace be a place for art...?

The special one. Have a reference to this.

Nice space.

If you want to move your tv from the mantel, the nook, with some work, could provide a place for other media related items.

Have you considered putting your tv on the angled wall?

You might find or have built a cabinet to slip into the indent that could be used for storage. Depending upon what furnishings you plan for that wall, you could add wainscoting to that entire wall and have disappearing wood doors and create a hidden storage compartment-- perhaps even for a safe/lock box of file boxes for financial documents -- in front of which you could add furnishings, including adding the tv to the wall. If you don't want the wainscoting as high as the opening, you could create an open shelf or shelf w/hinged top door or even a top drawer above the wainscoting and place media related items there.

Alternately, you could frame around the inside of the nook and have the equivalent of upscale glass front kitchen cabinet doors built to cover the opening. Adding shelves then gives you a curio cabinet w/electrical outlets for lights inside if you choose glass shelves.

Adding solid doors gives you out-of-sight storage and/or, adding a pet door, gives your pet it's own space out of human foot traffic areas.

Idk why tv can't sit at top front edge of the boxy opening? and console under it.

You should be able to enclose the tv nook as you mentioned. You will need to use a cabinet door for the opening about 3ft high, not a full sized door.

Filling in the arch doesn't compromise it in any way. you could frame in and fill the archway down to 7' and add doors on the front door side.

This would allow you to have a long flat wall in the family room for your TV.

It looks to be making a fine pet bed, but I would dry wall the nook out of existence. A TV there would be right in the traffic path. With a solid wall there you could add an armoire to serve as the additional closet.

In a room with sliding patio door(s) making furniture placement challenging, consider choosing smaller furnishings as well as choosing -- or adding -- castors to some furnishing so they could be moved about more easily.

I still am lost, cause the empty spot would keep the tv out of walk traffic.... is it too low in there? even at the top. or mount it just above.

TV consoles tend to only be about 18" deep, you would have more then enough room for that to go along your new wall.

Your path of traffic appears to be out where you have the black rugs- probably 30" away from the flat wall.

I would then turn the chairs around to face the fireplace and add a small accent table between them. You could turn the sofa (in front of the patio doors) leaving enough space for traffic flow (42") and then add two smaller accent chairs with their backs to the TV.

As it is now your furniture is to far apart for comfortable conversation.

I risk being a broken record - I see an arched opening - for people - I'd put the tv flat against that wall, or tucked right inside 'open box', at the top for good viewing.