Thanks RDB for your prompt response.
As I frequently travel on this train, I have been made to understand by the TC and coach attendants that every Rajdhani that goes to New Delhi, returns as a August kranti and vice versa for August Kranti converting into Rajdhani while returning from New Delhi. So in essence, either my information is incorrect or WR wll stop the rake exchanging arrangement at New Delhi till December. The latter looks remote to happen. So not sure how this will not affect August Kranti.