I have some idea's to continue:
8) Make it run from 8-24V input like the Intel DN2800MT board does to minimize the amount of power supply wires required.
9) Have 2 mini PCIe slots, with at least one full size supporting 240GB mSATA SSD drives.
10) Have an HDMI port facing inside, so people can use the board in a DDIN case with HDMI screen without looping an external cable back in.
11) Spend $50 on a high quality audio DAC instead of a cheap realtek sound DAC... It does make a difference!
12) Work with the JoyCon guy to integrate steering wheel control hardware.