I have a couple machines I built that are run by Arduino Megas. They work well enough but more speed and memory would be useful.
There is the Arduino Due that has more memory and is faster but its I/O is 3.3v, unlike the Mega that uses 5v. The Due speed increase would be nice but changing all the connected devices to work on 3.3 isn’t real convenient (yea I know there is converter boards out there, but still).
There is an Edison GPIO board shown, but it doesn’t have much I/O and it’s not 5v logic, so it’s not very convenient for someone trying to ‘upgrade’ from an Arduino.
What would be real nice for the Edison is a IO board that has at least 54 I/O pins and lets you select the logic level (5v, 3.3v or 1.8v). Each pin would not need to be changeable, just groups of pins (the mega has 7 groups of pins). The setting could be a physical jumper, since this isn’t something that would need to be changed while the device was running.
The configuration of the pins could be argued both ways. If you make them in the same locations as the Mega, then you’ll get complaints about “shields not working” when trying to run the Mega pin configuration. That could be fixed in the sketches tho.
The reason for 54 pins is because that’s what the Mega has. Anyone who needed more I/O would already have muxing boards for that, that they could hook up to the Edison board–that is, if you could set the logic levels for the I/O banks.
Lastly, the power supply on the board would need to accept a range of at least 5 -12V, since that is the range of power supplies people commonly use for the Arduino boards.