If extended to MAO stoppages needs to be increased and it can't be a Duronto. Most stations in this route are not connected to Goa, now the JSME-VSG is serving a bit for ROU/JSG etc. but TATA-CKP don't have Goa connectivity.
one day slot is empty throughout the route, I know atleast upto ROU its free.. am unaware after that.. In that case they can easily introduce a SF Exp with more stops like KGP-CKP-ROU-JSG etc to Goa.