So given the Apple Smart keyboard and the new iPad Pro 9.7" model one thing that could be a great differentiator for the TB is being back lit. My MacBook Pro has a backlit keyboard and it's very effective. The only other back lit keyboard I know of it the Logitec one, but the case is rather large and ugly (and not flexible in terms of configuration)
I doubt the Apple Smart keyboard could ever be backlit given the thin design, but looking that the videos I'd guess it might be possible (maybe by creating a cut out in the butterfly blades) for the TB to have a LED per key. If you wanted to get really adventurous you could use a multi colour LED and have it change depending on the selected modes, for example when in editing mode only illuminate the keys that support editing (the green highlight in your video looks good, I was very disappointed when I saw other videos that seemed to show a solid key cap.) If you do this I also vote for a psychedelic mode with random colour phasing across all the keys
Of course to preserve the battery you'd need a mechanism (maybe via the app ?) to control when the LEDs were in use and the brightness level.
IMPORTANT. Please do not make changes to accommodate this idea in the first HW release, it would only cause further delays. However if you wanted to do it in the next version (and offer the upgrade under the early adopter guarantee) It'd be great.