does the "electronic system" automatically bring cash & futures prices together if there is a wide point difference?
I know that cash-futures arbitragers (hedgers and speculators) do this most of the time, but what happened if they didn't? Would the "electronic system" kick in and force an arbitrage between them?
Which "electronic system" are you talking about?
The premise that no-one would step in to take a "risk-free" arbitrage doesn't make sense.
I think adequate links have been provided for you on this matter in your other two threads.