Can the glass shelves be removed? Then you could paint or paper the back and add one large art piece.

Even painting it a fun color like kiwi green and adding new glasses would take this a long way.

I think the pure white and glass are dating the niche. I would paint the inside of it the same high gloss light gray for a cohesive look to your dining room. And definitely consider removing the shelves and place one large piece in the niche instead of the smaller knick knacks. If you can manage a spot light inside it will look great. Not sure of what style you like but here are some inspiration pics...