A few layout options :
If we Sheetrock over the fireplace you can do a sectional, with the long part against the FP wall. And the chaise piece on the window wall.
Then the tv can go on the mirror wall.
Either on a swingable arm. Or regular.
Another idea would be to keep the FP. And have the tv on the mirror wall with sofa against the windows and the two chairs on the left of that.
Would you consider a slip cover over the sofa to brighten things up (no clue where you’d even get one and if it would look nice on that shape. But may be worth the try)
Or sofa on the mirror wall. And the two chairs across the tv
Regardless I think in all situations you should have a swing arm for the tv to maximize the practicality.
Sounds like thats your priority. Rightfully so :)
I would then remove what you know your are ridding of.
I.E. remove the tv bookcase and the rug, and whatever else you plan to change.
And start afresh.
Try out some furniture layouts, and pick what’s most comfortable for you.
And then we decorate!!!
I also want to see the FP uncovered. And see if it’s worth featuring or possibly covering up.
Decorate after you know what you plan to do with the space. So you can design around that!
Q