I'm surprised that there hasn't more interest in this over the years (judging by these forums), just the odd query that seemed to relate.
Maybe an easy-ish alternative would be a public server which has a number of Phidgets connected, and to which one could connect?
At least for input-only devices, there might not be any contention problem. And perhaps for outputs, users could be rationed by a queuing system or some such.
Is this something you might consider providing, if more folk were interested?