Dp you want to put bookcases in the voids?

Actually there will be built in shelves up to the niches

Are you suggesting the drywall portion would only cover the bump out?

Nup , why remove the texture the painted brink offers in an otherwise bland surface?

What if we left it textured and just put up the tv on the existing chimney?

That’s an option worth exploring.

Is there a reason why you can’t remove the old chimney?

No other option for the TV? Placing it over the fireplace is common but not optimum.

Have you figured out a layout for the furnishings in the room?

So many hurdles with hiding wires and cables if you just place the TV on the brick. Also, there's an issue of what size screen looks appropriate over a fireplace.

Show us pics of all four walls in this large space and post a drawing. Why pit the TV on this wall? Let’s find another space for it and different orientation for the sofa.

Here are the other areas— back door entering into the kitchen and flowing into the family room.

just wondering, there is actually no firebox there is there? Is the room actually enclosing what was once an external wall with the chimney of another rooms fireplace in it? It’s the chimney that is the location in question isn’t it? Just getting a tad confused when I can only see the back side of a chimney, not an actual fireplace when others have commented on fireplaces and tv placement! So any tv could be on a console and wouldn’t have to be mounted would it? That could look quite ok without the tv being placed too high. The arch of the chimney could create a nice frame over the top.

It probably comes down to whether you want a clinical look of an all modern room or a look that is characterful. My vote would be characterful as the windows are saying character than streamlined modern to me