One of the biggest cons is that above the tv is way too high for most people's optimal/comfortable viewing. There are several different opinions about the best height at which to view a tv, but generally when sitting you should be staring at the center of the screen or at the very highest at the bottom of the tv. Unless you have an unusually low-profile fireplace, watch tv standing or are like 6' 6" tall, a tv mounted above the fireplace is going to make for some uncomfortable viewing.

can you do search on previous discussions on the dilemma section of Houzz - you will see this often comes up. Bottom line, it is not a good idea as heat and a tv don't go well.

Might I suggest a more contemporary picture frame mantel with mosaic stone tile between that and your firebox? Love the near craftsman window shapes flanking the fire wall . . . use the height on both sides, / shallow shelves on one side can visually frame a swing arm for your television and give real storage on the other side.

You could really use anything - I do support the no fire arms idea. Look at your hobbies e.g if you are into sailing maybe some Oars, cycling a brightly covered wheel rim, gardening an antique tool, antiques & collectables a brass beg warmer, music a gitar, violin or saxophone, or fishing rods etc if all else fails a massive traditional or highly decorative modern mirror which will throw the light around the room. Make it something that shows who you are & your personality. It must be a passion or somthing rhat brings you pleasure.