This might work but you should really test it out somehow, there is still alot of metal surrounding it that might end up decreasing the RF performance. That said tho, you usually have the keyboard pretty close to the computer, so it might not be an issue? You could do the bottom in acrylic? That also makes it possible to add underglow.
This is just my 2 cent: If you go the route of adding bluetooth, do it well or don't do it. Make sure that it is intuitive how to pair (or use dongle)
and make sure battery life is good. Otherwise it will only bring the keyboard down (imo). Since the design is centerd around the led's, which you would only use while being connected with the cable(?), I'd say a lack of bluetooth would not be that bad. That being said, I do encourage adding bluetooth, it is a great feature
What bluetooth solution (chips) are you considering?