If the CT is open circuit, then a very high voltage is possible across the CTs secondary terminals. The magnitude of the voltage is dependant on the primary current through the CT and the size of the CT (normally, the bigger the core, the higher the voltage). Assuming these are protection class CTs, then the voltage is probably in the range of 30 kV peak or so. Note that the waveform is non-sinusoidal.
If the CT terminals are open, then there will probably be some flashovers between the terminals, depending on how close the are. If they are not sparking, then there is probably some internal flashing, and eventually there will be a short in the secondary winding. This causes high current flow and potentially high temperatures.
It's hard to say if the gear will fail or not, without more detail on the installation.
My advise.....take the outage. Besides equipment damage, it is a definate safety hazard!