If the compressor cannot operate (eg electrical plug smashed) or the air-line from the compressor is broken preventing any height or reservoir valve pressure increase then a serious suspension fault will occur. However usually if that message occurs then the vehicle is already on its way to the bump-stops, assuming the pilot exhaust valve solenoid is still operational.
An ABS fault does not trigger the 50kph message, only the safe height (access height) message.

