I put the TV on a separate wall than the wall which will eventually have a wood burning stove. (The mantle and backdrop is already in place. Right now I am dealing with homeowners insurance that doesn't want me to have one.) I don't watch much TV at all, and I really dislike - for me - having an ugly black box being the center of living room attention. When I have guests over, we're here to talk. I can think of exceedingly few occasions I'd be watching the idiot box with guests. Probably if they were here several days, we'd rent a movie or two via Amazon Prime. (Moot point right now, COVID and all.... but hopefully that won't last...) And with a wood burning stove, the exhaust pipe will go up and bisect the view of any TV over the mantle. I sat down on the couch to figure out the best viewing height - which is well below what the mantle might ever be, at least on this couch. It would be fine if I could lean back and rest my head, to have something over mantle height - assuming I'd go with a regular fireplace. But at six feet tall - there just isn't a couch or sofa like that. Plus as others have said, what about decorations? I enjoy decorating my mantle for various holidays! After all, that's really what mantles are for, right? The thing is off to the side, and it does not get glare there, either.

I would not do it. It puts unnecessary strain on your neck or forces people to lie back like the dead and it's hard enough to teach my kids to not slouch. You might not think the neck thing matters but we all get old .. if we're lucky. It also makes me feel like I'm in a bar, an airport, or a bad restaurant. Sorry, if that offends anyone, it's how I feel and so far all of my clients have agreed without needing any persuasion.But that doesn't mean it's wrong to do it. Only the owner's family needs to like it. To me it's just not that difficult to put the TV to one side with the great adjustable brackets now available. The proper height of a TV is easy to determine, just sit on a couch, look straight ahead, and have someone measure the point you feel comfortable looking at. Perhaps take an average of your family members. If I had to do it, I would at least put the fireplace box tight to the floor, the mantel low, and be able to enclose the TV when not in use. These things are not pretty. It would also help to recess it and tip it downward for better viewing and less reflected light. I was in an Italian restaurant in the 60's called Charlie's that had multiple gas fireplaces recessed into the wall above seated head height. Would that work?

I think you can still do it. If you look at the 2nd picture I posted above, you'll see that the fp is actually recessed into the surrounding bookshelves. So you can make the shelves on the right side, say (sorry I don't know metric) 10" deep and the ones on the right 18" deep. The fronts will line up and look even. You'd want something deeper where the tv and components go anyway as they tend to be deeper and need more air circulation to dissipate heat. You'd just have to watch code in your area for how close combustible materials can be to the fire box. Most likely this would need to be done custom. I know fireplaces look very permanent, but one thing I've learned in my years of looking at remodels is, there's a boat load more flexibility in fireplace surrounds than you think. More examples of recessed fireplaces:

I think if we had a wider fireplace insert it would make a big difference overall. That is something I stated was a misstep already. Our TV is recessed in alcove. The mantel and surrounding materials are approved for fireplace. It’s true there was significant work needed to have this meet code. I actually can’t imagine the mantel any higher as it is already at my chest height when I am near it. It really is so personal. The only thing I would shift is our fireplace insert size.