It makes no sense to design it to have no built-in memory, even the Clip+ has it. At least 2 GB is a must nowadays.
I would suggest at least 3 colour versions: black, silver, white.
Bluetooth, NFC, WiFi? Is it possible at this price point? After all an audio streaming is a worldwide trend...
DAB digital radio?
I think you're in the wrong thread. Audiophile DAPs are a niche market (even the cheaper ones) and the manufacturers don't have the funds to make different versions. This is not a plastic sansa where you can make thousands of colorful plastic housings coz first, it's not going to be plastic and second, Fiio is not that kind of company and even if their sells are good I don't think they will be matching the commercial sandisk and apple products in sales any time soon, though hopefully they'll do it in the near future.
And bluetooth, NFC and Wifi, dab radio - you surely are in the wrong thread.