here's a plausible fantasy, some software will include 3D-printable files describing a physical interface device, which can have some standard electronics plugged in

as long as it doesn't need to be hard realtime and infinitely reconfigurable, it's very feasible

like, imagine a game in which you hammer nails, you would 3D print a hammer, stick in an accelerometer module and mcu/battery/bluetooth module

point being, there are definitely ways to make interfaces that are now, or will become, really usable