If the rad fan goes you normally get a warning light or watch the gauge .If the CC stops working you won't know till you go slow .....
Didn't that happen to Dave Miles because the plug came off the pump? The ECU has a MAT sensor for a reason and with an ECU that you can play with, it's easy to write in some safety factors in the event of intake temps going bonkers.
Si - you won't be able to cool the intake charge down below ambient temperature unless you start playing with water injection. In all this stuff theory only gets you so far but everything I've read states pretty clearly that the colder the intake air, the better, assuming the engine is set up to take advantage of it. I bet your car feels faster on a day like today vs the height of summer - this is colder intake but also a more efficient intercooler.
From what I saw on Rob's the other day, the intake temps were a pretty solid 30 degrees which suggests that the sensor can't really read temperatures lower than the throttle body, but is definitely capable of reading higher.