There are many missing comments. Obviously you cannot support every IC, but supporting sensors would be reasonable. Most sensors have predictable behavior (at least theoretically) based on the amount or intensity of something (e.g. Hall effect and magnetic force, CO2 detectors, photoresistor, ECG, IR ToF range finders, pulse oximetry, accelerometers (including the 9 dimensional cards—I have one that also includes a barometer for elevation monitoring). Is a confusing jungle of prebuilt components that use SPI or I2C to communicate w/ an Arduino, Raspberry Pi, etc. but some really cool stuff for building IoT, robotics, etc.

Being able to add some communication modules (XBee, generic 2.4 GHz, SDLs, Bluetooth, WiFi), USB, Ethernet.

Maybe you could work w/ vendors like Spark Fun, AdaFruit, so that there are designs available for iCircuit.