These are AC-DC locos so even after DC-AC conversion they will continue to operate,
As of now only KYN-TNA-LTT is getting converted the conversion of CSTM will take 1-2 years more
These locos are just around 15-16 years old and replacing the entire fleet of 53 WCAM-3 and around 20 WCAM-2 locos would mean allotment of equal number of pure AC locos to KYN which is definitely time consuming, Hence it will take some time...