I see what you mean. First the scale of the TV Is too small for the wall. You could put pictures up, aor a collection of empty antique picture frames. I you have book case line them up on the wall. I would place some armchair facing into the room and position the couch so you create a conversation area.
This is also a high wall like yours. Creation the vignette combined with the tall mirror keeps the eye level lower and creates interest.
Hope this helps
plays with paints